<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019cd2cc-7218-7ac7-a9d3-9645cd3c98cf,g:befdeb73-1ec3-4f32-93fd-df49725d2b3e-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DocumentandEntityInformationDocument" xlink:type="simple" xlink:href="trs-20260331.xsd#DocumentandEntityInformationDocument"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DocumentandEntityInformationDocument" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitiesTable_019cd2cc-7389-7eaa-9a99-37e6e579a89d" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntitiesTable_019cd2cc-7389-7eaa-9a99-37e6e579a89d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019cd2cc-7389-76ca-aa48-826efd97cae8" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_EntitiesTable_019cd2cc-7389-7eaa-9a99-37e6e579a89d" xlink:to="loc_dei_LegalEntityAxis_019cd2cc-7389-76ca-aa48-826efd97cae8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019cd2cc-7389-76ca-aa48-826efd97cae8_default" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019cd2cc-7389-76ca-aa48-826efd97cae8" xlink:to="loc_dei_EntityDomain_019cd2cc-7389-76ca-aa48-826efd97cae8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019cd2cc-7389-715d-820e-446d5cac7994" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019cd2cc-7389-76ca-aa48-826efd97cae8" xlink:to="loc_dei_EntityDomain_019cd2cc-7389-715d-820e-446d5cac7994" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_019cd2cc-7389-7468-b61d-9843255e4680" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntityIncorporationStateCountryCode_019cd2cc-7389-7468-b61d-9843255e4680" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_019cd2cc-7389-7b85-ac51-c220ed556d0f" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_Security12bTitle_019cd2cc-7389-7b85-ac51-c220ed556d0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport_019cd2cc-7389-7fff-b622-14466926dd45" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentTransitionReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_DocumentTransitionReport_019cd2cc-7389-7fff-b622-14466926dd45" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentQuarterlyReport_019cd2cc-7389-7b81-8a67-6f72e89d51e6" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentQuarterlyReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_DocumentQuarterlyReport_019cd2cc-7389-7b81-8a67-6f72e89d51e6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_019cd2cc-7389-7424-b0f5-b05667a94756" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_DocumentPeriodEndDate_019cd2cc-7389-7424-b0f5-b05667a94756" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_019cd2cc-7389-7b95-b84c-536d71f4c90f" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_LocalPhoneNumber_019cd2cc-7389-7b95-b84c-536d71f4c90f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_019cd2cc-7389-75d9-916c-a1881393c5f1" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_CityAreaCode_019cd2cc-7389-75d9-916c-a1881393c5f1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_019cd2cc-7389-7bd5-9060-113ebfd6f240" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntityAddressPostalZipCode_019cd2cc-7389-7bd5-9060-113ebfd6f240" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_019cd2cc-7389-7c7d-b0b9-5ba8d0ba2df1" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntityAddressStateOrProvince_019cd2cc-7389-7c7d-b0b9-5ba8d0ba2df1" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_019cd2cc-7389-70c6-8c91-5eece55cfe20" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntityAddressCityOrTown_019cd2cc-7389-70c6-8c91-5eece55cfe20" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine2_019cd2cc-7389-7515-a4c7-2e9f619e77c9" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressAddressLine2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntityAddressAddressLine2_019cd2cc-7389-7515-a4c7-2e9f619e77c9" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_019cd2cc-7389-78fa-8bf0-6b8914f4bd47" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntityAddressAddressLine1_019cd2cc-7389-78fa-8bf0-6b8914f4bd47" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_019cd2cc-7389-7c26-b9d4-c90d69c7492d" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntityFileNumber_019cd2cc-7389-7c26-b9d4-c90d69c7492d" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany_019cd2cc-7389-796d-b485-a70179998b83" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityShellCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntityShellCompany_019cd2cc-7389-796d-b485-a70179998b83" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent_019cd2cc-7389-770a-8fd1-d2313267fb82" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityInteractiveDataCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntityInteractiveDataCurrent_019cd2cc-7389-770a-8fd1-d2313267fb82" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus_019cd2cc-7389-78ed-ab1d-528f9e0b04e0" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityCurrentReportingStatus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntityCurrentReportingStatus_019cd2cc-7389-78ed-ab1d-528f9e0b04e0" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_019cd2cc-7389-7caa-ae10-fa390d1809ce" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntityRegistrantName_019cd2cc-7389-7caa-ae10-fa390d1809ce" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_019cd2cc-7389-773f-81e1-9e1be7d03f33" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntityCentralIndexKey_019cd2cc-7389-773f-81e1-9e1be7d03f33" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate_019cd2cc-7389-7e14-afe6-c9d0c9e518f4" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_CurrentFiscalYearEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_CurrentFiscalYearEndDate_019cd2cc-7389-7e14-afe6-c9d0c9e518f4" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory_019cd2cc-7389-7213-9bce-8b2015e7811d" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityFilerCategory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntityFilerCategory_019cd2cc-7389-7213-9bce-8b2015e7811d" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_019cd2cc-7389-71af-abd7-5362f79cd1bb" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_DocumentType_019cd2cc-7389-71af-abd7-5362f79cd1bb" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus_019cd2cc-7389-720b-85f9-ffa92e0b2a3a" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentFiscalYearFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_DocumentFiscalYearFocus_019cd2cc-7389-720b-85f9-ffa92e0b2a3a" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus_019cd2cc-7389-745f-9136-7de4873b8975" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentFiscalPeriodFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_DocumentFiscalPeriodFocus_019cd2cc-7389-745f-9136-7de4873b8975" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_019cd2cc-7389-70ec-9a08-9e6e6984e621" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_AmendmentFlag_019cd2cc-7389-70ec-9a08-9e6e6984e621" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_019cd2cc-7389-77eb-9cc3-09d2f024d4b2" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityCommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_019cd2cc-7389-77eb-9cc3-09d2f024d4b2" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness_019cd2cc-7389-7f47-a96b-19aea7162986" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntitySmallBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntitySmallBusiness_019cd2cc-7389-7f47-a96b-19aea7162986" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_019cd2cc-7389-78c4-9ead-8f2913f5414b" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntityEmergingGrowthCompany_019cd2cc-7389-78c4-9ead-8f2913f5414b" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_019cd2cc-7389-7499-a965-0d3f556b3b4e" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_TradingSymbol_019cd2cc-7389-7499-a965-0d3f556b3b4e" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_019cd2cc-7389-7b74-be12-5c60cdf50810" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_SecurityExchangeName_019cd2cc-7389-7b74-be12-5c60cdf50810" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_019cd2cc-7389-7676-8340-034fd80c92f9" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019cd2cc-7389-7de6-94d2-7ce2d78fdd4f" xlink:to="loc_dei_EntityTaxIdentificationNumber_019cd2cc-7389-7676-8340-034fd80c92f9" xlink:type="arc" order="29"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/ConsolidatedBalanceSheetStatement" xlink:type="simple" xlink:href="trs-20260331.xsd#ConsolidatedBalanceSheetStatement"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/ConsolidatedBalanceSheetStatement" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019cd2cc-7389-730f-b752-c82ebe4dafa7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019cd2cc-7389-7a48-a289-a91bc6e77ce3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-730f-b752-c82ebe4dafa7" xlink:to="loc_us-gaap_StatementTable_019cd2cc-7389-7a48-a289-a91bc6e77ce3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019cd2cc-7389-78a9-8683-026eae9df670" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019cd2cc-7389-7a48-a289-a91bc6e77ce3" xlink:to="loc_srt_StatementScenarioAxis_019cd2cc-7389-78a9-8683-026eae9df670" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019cd2cc-7389-78a9-8683-026eae9df670_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_019cd2cc-7389-78a9-8683-026eae9df670" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019cd2cc-7389-78a9-8683-026eae9df670_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019cd2cc-7389-7b0d-afff-a2c870aed98b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_019cd2cc-7389-78a9-8683-026eae9df670" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019cd2cc-7389-7b0d-afff-a2c870aed98b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_019cd2cc-7389-71bf-9d8b-c1a558eba1c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-730f-b752-c82ebe4dafa7" xlink:to="loc_us-gaap_AssetsAbstract_019cd2cc-7389-71bf-9d8b-c1a558eba1c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_019cd2cc-7389-7db5-b20c-8d4638403073" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019cd2cc-7389-71bf-9d8b-c1a558eba1c9" xlink:to="loc_us-gaap_AssetsCurrentAbstract_019cd2cc-7389-7db5-b20c-8d4638403073" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019cd2cc-7389-7b7a-b4d2-b55a58e30c92" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019cd2cc-7389-7db5-b20c-8d4638403073" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019cd2cc-7389-7b7a-b4d2-b55a58e30c92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_019cd2cc-7389-717d-93d8-71b1b282182f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019cd2cc-7389-7db5-b20c-8d4638403073" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_019cd2cc-7389-717d-93d8-71b1b282182f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet_019cd2cc-7389-7f44-a2c9-c4ea95ad1fd1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InventoryNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019cd2cc-7389-7db5-b20c-8d4638403073" xlink:to="loc_us-gaap_InventoryNet_019cd2cc-7389-7f44-a2c9-c4ea95ad1fd1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_019cd2cc-7389-7d46-8295-83076f32454a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019cd2cc-7389-7db5-b20c-8d4638403073" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_019cd2cc-7389-7d46-8295-83076f32454a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_019dcef5-01f8-72ce-b9ce-89dccc37086b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019cd2cc-7389-7db5-b20c-8d4638403073" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_019dcef5-01f8-72ce-b9ce-89dccc37086b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_019cd2cc-7389-751b-b6da-31a4aae50000" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019cd2cc-7389-7db5-b20c-8d4638403073" xlink:to="loc_us-gaap_AssetsCurrent_019cd2cc-7389-751b-b6da-31a4aae50000" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019cd2cc-7389-785d-8866-88f7ad86d71f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019cd2cc-7389-71bf-9d8b-c1a558eba1c9" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019cd2cc-7389-785d-8866-88f7ad86d71f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_019cd2cc-7389-7428-936e-92a393399023" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019cd2cc-7389-71bf-9d8b-c1a558eba1c9" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_019cd2cc-7389-7428-936e-92a393399023" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019cd2cc-7389-7289-b8a1-ce7df59b2396" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019cd2cc-7389-71bf-9d8b-c1a558eba1c9" xlink:to="loc_us-gaap_Goodwill_019cd2cc-7389-7289-b8a1-ce7df59b2396" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019cd2cc-7389-76d4-a2a5-38dfba125afa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019cd2cc-7389-71bf-9d8b-c1a558eba1c9" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019cd2cc-7389-76d4-a2a5-38dfba125afa" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_019cd2cc-7389-76b7-9fd4-2ce0bb787a38" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019cd2cc-7389-71bf-9d8b-c1a558eba1c9" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_019cd2cc-7389-76b7-9fd4-2ce0bb787a38" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_019cd2cc-7389-76aa-8c6b-a0b8ae66c4db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019cd2cc-7389-71bf-9d8b-c1a558eba1c9" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_019cd2cc-7389-76aa-8c6b-a0b8ae66c4db" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent_019dcef5-3a47-718c-8eb5-060d89c44c7e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019cd2cc-7389-71bf-9d8b-c1a558eba1c9" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent_019dcef5-3a47-718c-8eb5-060d89c44c7e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019cd2cc-7389-752d-b4c9-0da9770f03c0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019cd2cc-7389-71bf-9d8b-c1a558eba1c9" xlink:to="loc_us-gaap_Assets_019cd2cc-7389-752d-b4c9-0da9770f03c0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019cd2cc-7389-7ec7-90d1-b46d33f67dbe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-730f-b752-c82ebe4dafa7" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019cd2cc-7389-7ec7-90d1-b46d33f67dbe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_019cd2cc-7389-772f-ad61-58068f50cc62" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019cd2cc-7389-7ec7-90d1-b46d33f67dbe" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_019cd2cc-7389-772f-ad61-58068f50cc62" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtCurrent_019cd2cc-7389-7127-8717-bcc85c6d7b7f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019cd2cc-7389-772f-ad61-58068f50cc62" xlink:to="loc_us-gaap_DebtCurrent_019cd2cc-7389-7127-8717-bcc85c6d7b7f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_019cd2cc-7389-7b0c-a334-f18c65013c59" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019cd2cc-7389-772f-ad61-58068f50cc62" xlink:to="loc_us-gaap_AccountsPayableCurrent_019cd2cc-7389-7b0c-a334-f18c65013c59" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_019cd2cc-7389-786b-bd1d-0bcb6e120481" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019cd2cc-7389-772f-ad61-58068f50cc62" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_019cd2cc-7389-786b-bd1d-0bcb6e120481" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LeaseLiabilitiesCurrentPortion_019cd2cc-7389-762c-916d-b5a5cf5e63e0" xlink:href="trs-20260331.xsd#trs_LeaseLiabilitiesCurrentPortion"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019cd2cc-7389-772f-ad61-58068f50cc62" xlink:to="loc_trs_LeaseLiabilitiesCurrentPortion_019cd2cc-7389-762c-916d-b5a5cf5e63e0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_019dcef5-64c4-7836-85a1-1757b439f889" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019cd2cc-7389-772f-ad61-58068f50cc62" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_019dcef5-64c4-7836-85a1-1757b439f889" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_019cd2cc-7389-7f1d-bb0b-a99e0632b110" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019cd2cc-7389-772f-ad61-58068f50cc62" xlink:to="loc_us-gaap_LiabilitiesCurrent_019cd2cc-7389-7f1d-bb0b-a99e0632b110" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_019cd2cc-7389-7af7-9775-95060f7be28e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019cd2cc-7389-7ec7-90d1-b46d33f67dbe" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_019cd2cc-7389-7af7-9775-95060f7be28e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LeaseLiabilitiesNoncurrent_019cd2cc-7389-7eac-af9e-64f62a98b306" xlink:href="trs-20260331.xsd#trs_LeaseLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019cd2cc-7389-7ec7-90d1-b46d33f67dbe" xlink:to="loc_trs_LeaseLiabilitiesNoncurrent_019cd2cc-7389-7eac-af9e-64f62a98b306" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_019cd2cc-7389-7867-a808-be5fca8f47ad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019cd2cc-7389-7ec7-90d1-b46d33f67dbe" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_019cd2cc-7389-7867-a808-be5fca8f47ad" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_019cd2cc-7389-7de5-b7a1-7dda4cf190e4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019cd2cc-7389-7ec7-90d1-b46d33f67dbe" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_019cd2cc-7389-7de5-b7a1-7dda4cf190e4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent_019dcef5-a253-79a2-98bf-6a0e2bcca13a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019cd2cc-7389-7ec7-90d1-b46d33f67dbe" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent_019dcef5-a253-79a2-98bf-6a0e2bcca13a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_019cd2cc-7389-7ae9-b225-54e833ec6dda" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019cd2cc-7389-7ec7-90d1-b46d33f67dbe" xlink:to="loc_us-gaap_Liabilities_019cd2cc-7389-7ae9-b225-54e833ec6dda" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_019cd2cc-7389-72fa-8d82-58191ed8c16a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019cd2cc-7389-7ec7-90d1-b46d33f67dbe" xlink:to="loc_us-gaap_PreferredStockValue_019cd2cc-7389-72fa-8d82-58191ed8c16a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_019cd2cc-7389-739a-8079-1216f15bd3ec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019cd2cc-7389-7ec7-90d1-b46d33f67dbe" xlink:to="loc_us-gaap_CommonStockValue_019cd2cc-7389-739a-8079-1216f15bd3ec" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalCommonStock_019cd2cc-7389-7887-90ec-2b3895c219a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019cd2cc-7389-7ec7-90d1-b46d33f67dbe" xlink:to="loc_us-gaap_AdditionalPaidInCapitalCommonStock_019cd2cc-7389-7887-90ec-2b3895c219a4" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019cd2cc-7389-79fe-a79f-927d781bc980" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019cd2cc-7389-7ec7-90d1-b46d33f67dbe" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019cd2cc-7389-79fe-a79f-927d781bc980" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019cd2cc-7389-78fe-a80b-35b038324c67" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019cd2cc-7389-7ec7-90d1-b46d33f67dbe" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019cd2cc-7389-78fe-a80b-35b038324c67" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019cd2cc-7389-7874-86d3-ae1571243ed3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019cd2cc-7389-7ec7-90d1-b46d33f67dbe" xlink:to="loc_us-gaap_StockholdersEquity_019cd2cc-7389-7874-86d3-ae1571243ed3" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_019cd2cc-7389-7510-b842-2ee869927efa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019cd2cc-7389-7ec7-90d1-b46d33f67dbe" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_019cd2cc-7389-7510-b842-2ee869927efa" xlink:type="arc" order="14"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/ConsolidatedBalanceSheetParentheticals" xlink:type="simple" xlink:href="trs-20260331.xsd#ConsolidatedBalanceSheetParentheticals"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/ConsolidatedBalanceSheetParentheticals" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019cd2cc-7389-7b98-a57b-23a581296eaa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019cd2cc-7389-75dd-a395-9d1e5cfc43e5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7b98-a57b-23a581296eaa" xlink:to="loc_us-gaap_StatementTable_019cd2cc-7389-75dd-a395-9d1e5cfc43e5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019cd2cc-7389-7acf-a3f3-6be239463474" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019cd2cc-7389-75dd-a395-9d1e5cfc43e5" xlink:to="loc_srt_StatementScenarioAxis_019cd2cc-7389-7acf-a3f3-6be239463474" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019cd2cc-7389-7acf-a3f3-6be239463474_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_019cd2cc-7389-7acf-a3f3-6be239463474" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019cd2cc-7389-7acf-a3f3-6be239463474_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019cd2cc-7389-7cf4-ae74-c5fbd1b3a6b2" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_019cd2cc-7389-7acf-a3f3-6be239463474" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019cd2cc-7389-7cf4-ae74-c5fbd1b3a6b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_019cd2cc-7389-7b28-8102-ddd1fddb2834" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7b98-a57b-23a581296eaa" xlink:to="loc_us-gaap_AssetsCurrentAbstract_019cd2cc-7389-7b28-8102-ddd1fddb2834" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_019cd2cc-7389-7e81-ab7d-9209e2d899a8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019cd2cc-7389-7b28-8102-ddd1fddb2834" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_019cd2cc-7389-7e81-ab7d-9209e2d899a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_019cd2cc-7389-74a1-8ec7-a93e7c141174" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7b98-a57b-23a581296eaa" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_019cd2cc-7389-74a1-8ec7-a93e7c141174" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_019cd2cc-7389-730d-aba3-6b0cc302ba84" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7b98-a57b-23a581296eaa" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_019cd2cc-7389-730d-aba3-6b0cc302ba84" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_019cd2cc-7389-700c-a6d8-4ccaad753d12" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7b98-a57b-23a581296eaa" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_019cd2cc-7389-700c-a6d8-4ccaad753d12" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesIssued_019cd2cc-7389-7aed-ba4a-a2b8136cfb72" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7b98-a57b-23a581296eaa" xlink:to="loc_us-gaap_PreferredStockSharesIssued_019cd2cc-7389-7aed-ba4a-a2b8136cfb72" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_019cd2cc-7389-7ed8-9871-a8f161e10777" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7b98-a57b-23a581296eaa" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_019cd2cc-7389-7ed8-9871-a8f161e10777" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_019cd2cc-7389-7abd-ba11-f5d80e72a7ef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7b98-a57b-23a581296eaa" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_019cd2cc-7389-7abd-ba11-f5d80e72a7ef" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_019cd2cc-7389-7cd9-b9b0-7ddd946add71" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7b98-a57b-23a581296eaa" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_019cd2cc-7389-7cd9-b9b0-7ddd946add71" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_019cd2cc-7389-7f21-a6c1-e7fc84307d3b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7b98-a57b-23a581296eaa" xlink:to="loc_us-gaap_CommonStockSharesIssued_019cd2cc-7389-7f21-a6c1-e7fc84307d3b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019cd2cc-7389-7657-837f-3612e664d479" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7b98-a57b-23a581296eaa" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_019cd2cc-7389-7657-837f-3612e664d479" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/ConsolidatedStatementofIncome" xlink:type="simple" xlink:href="trs-20260331.xsd#ConsolidatedStatementofIncome"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/ConsolidatedStatementofIncome" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019cd2cc-7389-7a2a-8507-414f56e9038f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019cd2cc-7389-7fd7-bf96-12df7b2cd572" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7a2a-8507-414f56e9038f" xlink:to="loc_us-gaap_StatementTable_019cd2cc-7389-7fd7-bf96-12df7b2cd572" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019cd2cc-7389-763a-9dba-32d8b0a09c07" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019cd2cc-7389-7fd7-bf96-12df7b2cd572" xlink:to="loc_srt_StatementScenarioAxis_019cd2cc-7389-763a-9dba-32d8b0a09c07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019cd2cc-7389-763a-9dba-32d8b0a09c07_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_019cd2cc-7389-763a-9dba-32d8b0a09c07" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019cd2cc-7389-763a-9dba-32d8b0a09c07_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019cd2cc-7389-73c0-95d8-0bd67a09c590" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_019cd2cc-7389-763a-9dba-32d8b0a09c07" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019cd2cc-7389-73c0-95d8-0bd67a09c590" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019cd2cc-7389-7b3b-94b4-1dd99715812e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7a2a-8507-414f56e9038f" xlink:to="loc_us-gaap_Revenues_019cd2cc-7389-7b3b-94b4-1dd99715812e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_019cd2cc-7389-7ef8-800f-de523474d9ce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7a2a-8507-414f56e9038f" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_019cd2cc-7389-7ef8-800f-de523474d9ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_019cd2cc-7389-7aa9-bdeb-f727322d4ac4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GrossProfit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7a2a-8507-414f56e9038f" xlink:to="loc_us-gaap_GrossProfit_019cd2cc-7389-7aa9-bdeb-f727322d4ac4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019cd2cc-7389-7d93-be28-6e8f6235c237" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7a2a-8507-414f56e9038f" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019cd2cc-7389-7d93-be28-6e8f6235c237" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_019cd2cc-7389-724a-b5b3-9479ebe28b9d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7a2a-8507-414f56e9038f" xlink:to="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_019cd2cc-7389-724a-b5b3-9479ebe28b9d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetImpairment_019cd2cc-7389-7e6f-bc43-678212807e14" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillAndIntangibleAssetImpairment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7a2a-8507-414f56e9038f" xlink:to="loc_us-gaap_GoodwillAndIntangibleAssetImpairment_019cd2cc-7389-7e6f-bc43-678212807e14" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019cd2cc-7389-7576-adfe-62e9f0ae33f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7a2a-8507-414f56e9038f" xlink:to="loc_us-gaap_OperatingIncomeLoss_019cd2cc-7389-7576-adfe-62e9f0ae33f0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019cd2cc-7389-7ffd-9878-70883c6bad07" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NonoperatingIncomeExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7a2a-8507-414f56e9038f" xlink:to="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019cd2cc-7389-7ffd-9878-70883c6bad07" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019cd2cc-7389-70a1-ab4a-64d6754506f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019cd2cc-7389-7ffd-9878-70883c6bad07" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019cd2cc-7389-70a1-ab4a-64d6754506f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019cd2cc-7389-769d-90d6-d06dc0eb52b5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019cd2cc-7389-7ffd-9878-70883c6bad07" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019cd2cc-7389-769d-90d6-d06dc0eb52b5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_019cd2cc-7389-7309-a64e-0ee2cc0fc96e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019cd2cc-7389-7ffd-9878-70883c6bad07" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_019cd2cc-7389-7309-a64e-0ee2cc0fc96e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_019cd2cc-7389-7de9-86c7-d1838c0bfd5e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019cd2cc-7389-7ffd-9878-70883c6bad07" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_019cd2cc-7389-7de9-86c7-d1838c0bfd5e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019cd2cc-7389-73fc-bfd4-7f6f9554ff63" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7a2a-8507-414f56e9038f" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019cd2cc-7389-73fc-bfd4-7f6f9554ff63" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019cd2cc-7389-7e67-a104-6078b1e8193a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7a2a-8507-414f56e9038f" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019cd2cc-7389-7e67-a104-6078b1e8193a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_019cd2cc-7389-755c-ad43-acabdf95dc0b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7a2a-8507-414f56e9038f" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_019cd2cc-7389-755c-ad43-acabdf95dc0b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_019cd2cc-7389-7c85-b246-798907838f5f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7a2a-8507-414f56e9038f" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_019cd2cc-7389-7c85-b246-798907838f5f" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019cd2cc-7389-74c1-b57e-2bb0cff3fe8c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7a2a-8507-414f56e9038f" xlink:to="loc_us-gaap_NetIncomeLoss_019cd2cc-7389-74c1-b57e-2bb0cff3fe8c" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicAbstract_019cd2cc-7389-75c2-a52d-a5299ce95afd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7a2a-8507-414f56e9038f" xlink:to="loc_us-gaap_EarningsPerShareBasicAbstract_019cd2cc-7389-75c2-a52d-a5299ce95afd" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsPerBasicShare_019cd2cc-7389-723a-8a3f-df5d864ded62" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsPerBasicShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019cd2cc-7389-75c2-a52d-a5299ce95afd" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsPerBasicShare_019cd2cc-7389-723a-8a3f-df5d864ded62" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare_019cd2cc-7389-7d69-9fc3-7c1afecde42d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019cd2cc-7389-75c2-a52d-a5299ce95afd" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare_019cd2cc-7389-7d69-9fc3-7c1afecde42d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_019cd2cc-7389-7b48-aedf-925ff9d5bf8b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019cd2cc-7389-75c2-a52d-a5299ce95afd" xlink:to="loc_us-gaap_EarningsPerShareBasic_019cd2cc-7389-7b48-aedf-925ff9d5bf8b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019cd2cc-7389-7559-ab77-83a122f75993" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019cd2cc-7389-75c2-a52d-a5299ce95afd" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019cd2cc-7389-7559-ab77-83a122f75993" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDilutedAbstract_019cd2cc-7389-764c-824f-9f6459e56287" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareDilutedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7a2a-8507-414f56e9038f" xlink:to="loc_us-gaap_EarningsPerShareDilutedAbstract_019cd2cc-7389-764c-824f-9f6459e56287" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare_019cd2cc-7389-7275-a179-91c8f652c5a0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_019cd2cc-7389-764c-824f-9f6459e56287" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare_019cd2cc-7389-7275-a179-91c8f652c5a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare_019cd2cc-7389-7ce9-b1da-dcb2012b025c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_019cd2cc-7389-764c-824f-9f6459e56287" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare_019cd2cc-7389-7ce9-b1da-dcb2012b025c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019cd2cc-7389-7ae5-b42d-2ae5888e8a59" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_019cd2cc-7389-764c-824f-9f6459e56287" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019cd2cc-7389-7ae5-b42d-2ae5888e8a59" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019cd2cc-7389-7078-bfd9-b89d37d725f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_019cd2cc-7389-764c-824f-9f6459e56287" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019cd2cc-7389-7078-bfd9-b89d37d725f0" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/ConsolidatedStatementofCashFlowsStatement" xlink:type="simple" xlink:href="trs-20260331.xsd#ConsolidatedStatementofCashFlowsStatement"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/ConsolidatedStatementofCashFlowsStatement" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019cd2cc-7389-74a7-8e00-82ca5769b3c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019cd2cc-7389-72ff-9b84-e7bc623e8503" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-74a7-8e00-82ca5769b3c2" xlink:to="loc_us-gaap_StatementTable_019cd2cc-7389-72ff-9b84-e7bc623e8503" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019cd2cc-7389-7e7e-ba0d-8e4eb7dd1a6d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019cd2cc-7389-72ff-9b84-e7bc623e8503" xlink:to="loc_srt_StatementScenarioAxis_019cd2cc-7389-7e7e-ba0d-8e4eb7dd1a6d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019cd2cc-7389-7e7e-ba0d-8e4eb7dd1a6d_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_019cd2cc-7389-7e7e-ba0d-8e4eb7dd1a6d" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019cd2cc-7389-7e7e-ba0d-8e4eb7dd1a6d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019cd2cc-7389-7744-a5f6-011f58ee819f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_019cd2cc-7389-7e7e-ba0d-8e4eb7dd1a6d" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019cd2cc-7389-7744-a5f6-011f58ee819f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-74a4-b3ea-a5893fa92353" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-74a7-8e00-82ca5769b3c2" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-74a4-b3ea-a5893fa92353" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperations_019dc105-e730-7360-82a9-0cff89ca0e5e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-74a4-b3ea-a5893fa92353" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperations_019dc105-e730-7360-82a9-0cff89ca0e5e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_019dc105-e730-7e80-84e5-8f693adf924e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-74a4-b3ea-a5893fa92353" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_019dc105-e730-7e80-84e5-8f693adf924e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019cd2cc-7389-703d-b663-61706b7ff44c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-74a4-b3ea-a5893fa92353" xlink:to="loc_us-gaap_ProfitLoss_019cd2cc-7389-703d-b663-61706b7ff44c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-74a4-b3ea-a5893fa92353" xlink:to="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetImpairment_019cd2cc-7389-79dc-aabc-ced03edeeb69" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillAndIntangibleAssetImpairment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:to="loc_us-gaap_GoodwillAndIntangibleAssetImpairment_019cd2cc-7389-79dc-aabc-ced03edeeb69" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDispositionOfAssets1_019cd2cc-7389-7aec-b8a6-d7767c97f0c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnDispositionOfAssets1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:to="loc_us-gaap_GainLossOnDispositionOfAssets1_019cd2cc-7389-7aec-b8a6-d7767c97f0c3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_019cd2cc-7389-7651-93c0-b89d409b23cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:to="loc_us-gaap_Depreciation_019cd2cc-7389-7651-93c0-b89d409b23cc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_019cd2cc-7389-7f8f-b4b8-13f9ae78d3e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_019cd2cc-7389-7f8f-b4b8-13f9ae78d3e2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_019cd2cc-7389-7ec8-acfc-6167676b5c0e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:to="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_019cd2cc-7389-7ec8-acfc-6167676b5c0e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_019cd2cc-7389-752f-99f9-fc88cc0eef71" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredIncomeTaxesAndTaxCredits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:to="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_019cd2cc-7389-752f-99f9-fc88cc0eef71" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_019cd2cc-7389-7ccf-a9e1-c753aec016fd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:to="loc_us-gaap_ShareBasedCompensation_019cd2cc-7389-7ccf-a9e1-c753aec016fd" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts_019cd2cc-7389-702c-8c48-d2529fd8df5e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProvisionForDoubtfulAccounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:to="loc_us-gaap_ProvisionForDoubtfulAccounts_019cd2cc-7389-702c-8c48-d2529fd8df5e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Increasedecreaseinasbestosliability_019cd2cc-7389-7503-b1c6-9d239c23c945" xlink:href="trs-20260331.xsd#trs_Increasedecreaseinasbestosliability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:to="loc_trs_Increasedecreaseinasbestosliability_019cd2cc-7389-7503-b1c6-9d239c23c945" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalExpenseAndLiabilities_019cd2cc-7389-7b9b-aeeb-c172b67a99bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EnvironmentalExpenseAndLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:to="loc_us-gaap_EnvironmentalExpenseAndLiabilities_019cd2cc-7389-7b9b-aeeb-c172b67a99bb" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_019cd2cc-7389-71f9-840e-08f9ac97e48c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:to="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_019cd2cc-7389-71f9-840e-08f9ac97e48c" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInReceivables_019cd2cc-7389-74c3-b623-4205792da038" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:to="loc_us-gaap_IncreaseDecreaseInReceivables_019cd2cc-7389-74c3-b623-4205792da038" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInventories_019cd2cc-7389-720a-9708-248ee64e60d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInInventories"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:to="loc_us-gaap_IncreaseDecreaseInInventories_019cd2cc-7389-720a-9708-248ee64e60d7" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_019cd2cc-7389-7b0d-8299-595e821a7ff1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_019cd2cc-7389-7b0d-8299-595e821a7ff1" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_019cd2cc-7389-7ed6-a574-23d0acf5a710" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_019cd2cc-7389-7ed6-a574-23d0acf5a710" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_019cd2cc-7389-731b-9a9f-ac55ca5adc82" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherOperatingActivitiesCashFlowStatement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-7cb6-abd1-5466df8410b1" xlink:to="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_019cd2cc-7389-731b-9a9f-ac55ca5adc82" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019cd2cc-7389-72fd-a582-e0f06a41aa26" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019cd2cc-7389-74a4-b3ea-a5893fa92353" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019cd2cc-7389-72fd-a582-e0f06a41aa26" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019cd2cc-7389-702b-a8a5-5221a8882098" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-74a7-8e00-82ca5769b3c2" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019cd2cc-7389-702b-a8a5-5221a8882098" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireProductiveAssets_019cd2cc-7389-76cc-90e0-c2cd8b7092a8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019cd2cc-7389-702b-a8a5-5221a8882098" xlink:to="loc_us-gaap_PaymentsToAcquireProductiveAssets_019cd2cc-7389-76cc-90e0-c2cd8b7092a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019cd2cc-7389-70c1-9950-2f5114ef79a9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019cd2cc-7389-702b-a8a5-5221a8882098" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019cd2cc-7389-70c1-9950-2f5114ef79a9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForProceedsFromHedgeInvestingActivities_019cd2cc-7389-78e8-923e-30829b6a48cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForProceedsFromHedgeInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019cd2cc-7389-702b-a8a5-5221a8882098" xlink:to="loc_us-gaap_PaymentsForProceedsFromHedgeInvestingActivities_019cd2cc-7389-78e8-923e-30829b6a48cd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForProceedsFromDerivativeInstrumentInvestingActivities_019cd2cc-7389-7876-b99a-d2c752ff736c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForProceedsFromDerivativeInstrumentInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019cd2cc-7389-702b-a8a5-5221a8882098" xlink:to="loc_us-gaap_PaymentsForProceedsFromDerivativeInstrumentInvestingActivities_019cd2cc-7389-7876-b99a-d2c752ff736c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_019cd2cc-7389-7516-ae41-c4dcaa1f05c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019cd2cc-7389-702b-a8a5-5221a8882098" xlink:to="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_019cd2cc-7389-7516-ae41-c4dcaa1f05c3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations_019cd2cc-7389-7896-af61-ef357ed80929" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019cd2cc-7389-702b-a8a5-5221a8882098" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations_019cd2cc-7389-7896-af61-ef357ed80929" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations_019cd2cc-7389-7059-b463-de3b2dfe4824" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019cd2cc-7389-702b-a8a5-5221a8882098" xlink:to="loc_us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations_019cd2cc-7389-7059-b463-de3b2dfe4824" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019cd2cc-7389-7af2-ac3a-7c8c6432f596" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019cd2cc-7389-702b-a8a5-5221a8882098" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019cd2cc-7389-7af2-ac3a-7c8c6432f596" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019cd2cc-7389-75cb-87df-12912fef9536" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-74a7-8e00-82ca5769b3c2" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019cd2cc-7389-75cb-87df-12912fef9536" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarlyRepaymentOfSeniorDebt_019cd2cc-7389-713b-9933-b6d88e85fc43" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarlyRepaymentOfSeniorDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019cd2cc-7389-75cb-87df-12912fef9536" xlink:to="loc_us-gaap_EarlyRepaymentOfSeniorDebt_019cd2cc-7389-713b-9933-b6d88e85fc43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt_019cd2cc-7389-77fd-8057-b4019110c060" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019cd2cc-7389-75cb-87df-12912fef9536" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt_019cd2cc-7389-77fd-8057-b4019110c060" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_019cd2cc-7389-7cfc-944e-51c54bd324f5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019cd2cc-7389-75cb-87df-12912fef9536" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_019cd2cc-7389-7cfc-944e-51c54bd324f5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLinesOfCredit_019cd2cc-7389-7844-bbd5-f27212a6171e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RepaymentsOfLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019cd2cc-7389-75cb-87df-12912fef9536" xlink:to="loc_us-gaap_RepaymentsOfLinesOfCredit_019cd2cc-7389-7844-bbd5-f27212a6171e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_019cd2cc-7389-720b-b080-50c79a26b6ea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfDebtExtinguishmentCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019cd2cc-7389-75cb-87df-12912fef9536" xlink:to="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_019cd2cc-7389-720b-b080-50c79a26b6ea" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_019cd2cc-7389-7796-a8ca-5c43e99d1594" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019cd2cc-7389-75cb-87df-12912fef9536" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_019cd2cc-7389-7796-a8ca-5c43e99d1594" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_019cd2cc-7389-7735-8a9c-f259a68783f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019cd2cc-7389-75cb-87df-12912fef9536" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_019cd2cc-7389-7735-8a9c-f259a68783f0" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividends_019cd2cc-7389-7336-a1e8-4383616488fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfDividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019cd2cc-7389-75cb-87df-12912fef9536" xlink:to="loc_us-gaap_PaymentsOfDividends_019cd2cc-7389-7336-a1e8-4383616488fb" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_019cd2cc-7389-72f0-8271-cead9bc638e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromPaymentsForOtherFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019cd2cc-7389-75cb-87df-12912fef9536" xlink:to="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_019cd2cc-7389-72f0-8271-cead9bc638e8" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations_019cd2cc-7389-704f-9047-d11cb6a26ae6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019cd2cc-7389-75cb-87df-12912fef9536" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations_019cd2cc-7389-704f-9047-d11cb6a26ae6" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations_019cd2cc-7389-7951-9bd7-d7716a9ffd4e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019cd2cc-7389-75cb-87df-12912fef9536" xlink:to="loc_us-gaap_CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations_019cd2cc-7389-7951-9bd7-d7716a9ffd4e" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019cd2cc-7389-766b-8751-39191da4c2f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019cd2cc-7389-75cb-87df-12912fef9536" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019cd2cc-7389-766b-8751-39191da4c2f0" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019cd2cc-7389-7b57-9b82-a8efd73707e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-74a7-8e00-82ca5769b3c2" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019cd2cc-7389-7b57-9b82-a8efd73707e8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_019cd2cc-7389-7f35-8ed8-eb8372841959" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-74a7-8e00-82ca5769b3c2" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_019cd2cc-7389-7f35-8ed8-eb8372841959" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_019cd2cc-7389-7245-8a39-cd8c6456d3c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract_019cd2cc-7389-7b7f-8e44-e5e4ba7f5c68" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplementalCashFlowInformationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-74a7-8e00-82ca5769b3c2" xlink:to="loc_us-gaap_SupplementalCashFlowInformationAbstract_019cd2cc-7389-7b7f-8e44-e5e4ba7f5c68" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPaidNet_019cd2cc-7389-7576-a07b-0f0e5ba25380" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_019cd2cc-7389-7b7f-8e44-e5e4ba7f5c68" xlink:to="loc_us-gaap_InterestPaidNet_019cd2cc-7389-7576-a07b-0f0e5ba25380" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaid_019cd2cc-7389-74fc-8385-afbabb242e09" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxesPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_019cd2cc-7389-7b7f-8e44-e5e4ba7f5c68" xlink:to="loc_us-gaap_IncomeTaxesPaid_019cd2cc-7389-74fc-8385-afbabb242e09" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncashOrPartNoncashAcquisitionFixedAssetsAcquired1_019dcefb-ec6b-78ea-b907-21e87e451bc4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NoncashOrPartNoncashAcquisitionFixedAssetsAcquired1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_019cd2cc-7389-7b7f-8e44-e5e4ba7f5c68" xlink:to="loc_us-gaap_NoncashOrPartNoncashAcquisitionFixedAssetsAcquired1_019dcefb-ec6b-78ea-b907-21e87e451bc4" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/ConsolidatedStatementofShareholdersEquityStatement" xlink:type="simple" xlink:href="trs-20260331.xsd#ConsolidatedStatementofShareholdersEquityStatement"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/ConsolidatedStatementofShareholdersEquityStatement" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019cd2cc-7389-7bc4-8715-cd7ff91fa72f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019cd2cc-7389-79fd-bb97-0f0e91c670ac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7bc4-8715-cd7ff91fa72f" xlink:to="loc_us-gaap_StatementTable_019cd2cc-7389-79fd-bb97-0f0e91c670ac" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019cd2cc-7389-7f9c-a9c6-d83b953b15d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019cd2cc-7389-79fd-bb97-0f0e91c670ac" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019cd2cc-7389-7f9c-a9c6-d83b953b15d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019cd2cc-7389-7f9c-a9c6-d83b953b15d0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019cd2cc-7389-7f9c-a9c6-d83b953b15d0" xlink:to="loc_us-gaap_EquityComponentDomain_019cd2cc-7389-7f9c-a9c6-d83b953b15d0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019cd2cc-7389-7d7d-8418-7d85922147be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019cd2cc-7389-7f9c-a9c6-d83b953b15d0" xlink:to="loc_us-gaap_EquityComponentDomain_019cd2cc-7389-7d7d-8418-7d85922147be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ParentMember_019cd325-d458-7fe8-8998-5efdcbc808cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019cd2cc-7389-7d7d-8418-7d85922147be" xlink:to="loc_us-gaap_ParentMember_019cd325-d458-7fe8-8998-5efdcbc808cc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019cd2cc-7389-7e80-8209-f6e7fe7deb89" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_019cd325-d458-7fe8-8998-5efdcbc808cc" xlink:to="loc_us-gaap_CommonStockMember_019cd2cc-7389-7e80-8209-f6e7fe7deb89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019cd2cc-7389-7a8f-9967-d5885caaf5c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_019cd325-d458-7fe8-8998-5efdcbc808cc" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019cd2cc-7389-7a8f-9967-d5885caaf5c2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019cd2cc-7389-7040-9bdc-2ea27db82910" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_019cd325-d458-7fe8-8998-5efdcbc808cc" xlink:to="loc_us-gaap_RetainedEarningsMember_019cd2cc-7389-7040-9bdc-2ea27db82910" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019cd2cc-7389-73f9-9a60-4d2607de9154" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_019cd325-d458-7fe8-8998-5efdcbc808cc" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019cd2cc-7389-73f9-9a60-4d2607de9154" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019cd2cc-7389-72c2-9db5-a69a2119e9c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7bc4-8715-cd7ff91fa72f" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019cd2cc-7389-72c2-9db5-a69a2119e9c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019cd2cc-7389-755f-a348-01706f020fe3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7bc4-8715-cd7ff91fa72f" xlink:to="loc_us-gaap_NetIncomeLoss_019cd2cc-7389-755f-a348-01706f020fe3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019cd2cc-7389-7df5-ae2d-315f7bd13af0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7bc4-8715-cd7ff91fa72f" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019cd2cc-7389-7df5-ae2d-315f7bd13af0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019cd2cc-7389-73e3-ac4e-7adf55de0963" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7bc4-8715-cd7ff91fa72f" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019cd2cc-7389-73e3-ac4e-7adf55de0963" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_019cd2cc-7389-7760-bffc-21b1ecb437ef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7bc4-8715-cd7ff91fa72f" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_019cd2cc-7389-7760-bffc-21b1ecb437ef" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_019cd2cc-7389-7e65-b721-a84362584f29" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7bc4-8715-cd7ff91fa72f" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_019cd2cc-7389-7e65-b721-a84362584f29" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition_019cd2cc-7389-7aff-aaa3-633f2b07717c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7bc4-8715-cd7ff91fa72f" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition_019cd2cc-7389-7aff-aaa3-633f2b07717c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019cd2cc-7389-7989-8a9d-a49e07cc2a97" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7bc4-8715-cd7ff91fa72f" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019cd2cc-7389-7989-8a9d-a49e07cc2a97" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalDividendsInExcessOfRetainedEarnings_019cd2cc-7389-7347-b573-7c09a5544846" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalDividendsInExcessOfRetainedEarnings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7bc4-8715-cd7ff91fa72f" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalDividendsInExcessOfRetainedEarnings_019cd2cc-7389-7347-b573-7c09a5544846" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStockCash_019cd2cc-7389-7ffb-84bc-40c6ab5117f6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsCommonStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7389-7bc4-8715-cd7ff91fa72f" xlink:to="loc_us-gaap_DividendsCommonStockCash_019cd2cc-7389-7ffb-84bc-40c6ab5117f6" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019cd2cc-7389-71d8-82f9-07dd5cd73c87" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/BasisofPresentationSaleofAerospaceDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#BasisofPresentationSaleofAerospaceDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/BasisofPresentationSaleofAerospaceDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-7668-a49a-6fa586f51eff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-7b80-b0f4-6015828334e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-7668-a49a-6fa586f51eff" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-7b80-b0f4-6015828334e8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7389-74b3-87e9-6f24eb12b8eb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-7b80-b0f4-6015828334e8" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7389-74b3-87e9-6f24eb12b8eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-74b3-87e9-6f24eb12b8eb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7389-74b3-87e9-6f24eb12b8eb" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-74b3-87e9-6f24eb12b8eb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-7e62-b668-8ca12362b2d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7389-74b3-87e9-6f24eb12b8eb" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-7e62-b668-8ca12362b2d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LamonsDivisionMember_019cd2cc-7389-757c-afe5-4036ec4dfea0" xlink:href="trs-20260331.xsd#trs_LamonsDivisionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-7e62-b668-8ca12362b2d3" xlink:to="loc_trs_LamonsDivisionMember_019cd2cc-7389-757c-afe5-4036ec4dfea0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceReportableSegmentMember_019dceff-4e8d-7d46-997c-f582ad1f27a3" xlink:href="trs-20260331.xsd#trs_AerospaceReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-7e62-b668-8ca12362b2d3" xlink:to="loc_trs_AerospaceReportableSegmentMember_019dceff-4e8d-7d46-997c-f582ad1f27a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_019cd2cc-7389-79c2-9927-7c3b3b4cd912" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-7b80-b0f4-6015828334e8" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_019cd2cc-7389-79c2-9927-7c3b3b4cd912" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019cd2cc-7389-79c2-9927-7c3b3b4cd912_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019cd2cc-7389-79c2-9927-7c3b3b4cd912" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019cd2cc-7389-79c2-9927-7c3b3b4cd912_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019cd2cc-7389-75ff-8ffe-299ca4eefbaa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019cd2cc-7389-79c2-9927-7c3b3b4cd912" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019cd2cc-7389-75ff-8ffe-299ca4eefbaa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_019cd2cc-7389-7e48-ad3a-8115b786483b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationsDisposedOfBySaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_019cd2cc-7389-75ff-8ffe-299ca4eefbaa" xlink:to="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_019cd2cc-7389-7e48-ad3a-8115b786483b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Purchasepricebasedondefinitivesalesagreement_019cd2cc-7389-7914-8f28-b9e94c639f84" xlink:href="trs-20260331.xsd#trs_Purchasepricebasedondefinitivesalesagreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-7668-a49a-6fa586f51eff" xlink:to="loc_trs_Purchasepricebasedondefinitivesalesagreement_019cd2cc-7389-7914-8f28-b9e94c639f84" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_019dcefe-7d7a-7243-847a-7dbc921b9edd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-7668-a49a-6fa586f51eff" xlink:to="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_019dcefe-7d7a-7243-847a-7dbc921b9edd" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DiscontinuedOperationsSaleofAerospaceNarrativeDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#DiscontinuedOperationsSaleofAerospaceNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DiscontinuedOperationsSaleofAerospaceNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-75a2-9f0d-f605fdcf0df6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-7b93-803c-7bc2bb8393fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-75a2-9f0d-f605fdcf0df6" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-7b93-803c-7bc2bb8393fe" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019cd2cc-7389-715e-a1c6-41f8a41a75b8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-7b93-803c-7bc2bb8393fe" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019cd2cc-7389-715e-a1c6-41f8a41a75b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019cd2cc-7389-715e-a1c6-41f8a41a75b8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019cd2cc-7389-715e-a1c6-41f8a41a75b8" xlink:to="loc_us-gaap_EquityComponentDomain_019cd2cc-7389-715e-a1c6-41f8a41a75b8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019cd2cc-7389-7f90-bbff-6117556295cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019cd2cc-7389-715e-a1c6-41f8a41a75b8" xlink:to="loc_us-gaap_EquityComponentDomain_019cd2cc-7389-7f90-bbff-6117556295cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019cd2cc-7389-79d0-9538-cb31b52b7447" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019cd2cc-7389-7f90-bbff-6117556295cd" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019cd2cc-7389-79d0-9538-cb31b52b7447" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7389-76e7-a8e7-793f03a5518b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-7b93-803c-7bc2bb8393fe" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7389-76e7-a8e7-793f03a5518b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-76e7-a8e7-793f03a5518b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7389-76e7-a8e7-793f03a5518b" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-76e7-a8e7-793f03a5518b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-78a9-bf03-fca6fff364f6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7389-76e7-a8e7-793f03a5518b" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-78a9-bf03-fca6fff364f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LamonsDivisionMember_019cd2cc-7389-73df-95d5-5910cfa436a0" xlink:href="trs-20260331.xsd#trs_LamonsDivisionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-78a9-bf03-fca6fff364f6" xlink:to="loc_trs_LamonsDivisionMember_019cd2cc-7389-73df-95d5-5910cfa436a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceReportableSegmentMember_019dcf00-4f73-7b0b-93ea-18bdbfeaa9de" xlink:href="trs-20260331.xsd#trs_AerospaceReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-78a9-bf03-fca6fff364f6" xlink:to="loc_trs_AerospaceReportableSegmentMember_019dcf00-4f73-7b0b-93ea-18bdbfeaa9de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_019cd2cc-7389-72fe-9cae-cc5b3ed2683e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-7b93-803c-7bc2bb8393fe" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_019cd2cc-7389-72fe-9cae-cc5b3ed2683e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019cd2cc-7389-72fe-9cae-cc5b3ed2683e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019cd2cc-7389-72fe-9cae-cc5b3ed2683e" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019cd2cc-7389-72fe-9cae-cc5b3ed2683e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019cd2cc-7389-766d-a968-3ea7e2890251" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019cd2cc-7389-72fe-9cae-cc5b3ed2683e" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019cd2cc-7389-766d-a968-3ea7e2890251" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_019cd2cc-7389-7481-a0c7-975b890ad0f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationsDisposedOfBySaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_019cd2cc-7389-766d-a968-3ea7e2890251" xlink:to="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_019cd2cc-7389-7481-a0c7-975b890ad0f9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019dcf17-021f-72cf-a71e-aea247f9d5f3" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-7b93-803c-7bc2bb8393fe" xlink:to="loc_srt_RangeAxis_019dcf17-021f-72cf-a71e-aea247f9d5f3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019dcf17-021f-72cf-a71e-aea247f9d5f3_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019dcf17-021f-72cf-a71e-aea247f9d5f3" xlink:to="loc_srt_RangeMember_019dcf17-021f-72cf-a71e-aea247f9d5f3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019dcf17-021f-7423-8be9-0074aa8f2c7e" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019dcf17-021f-72cf-a71e-aea247f9d5f3" xlink:to="loc_srt_RangeMember_019dcf17-021f-7423-8be9-0074aa8f2c7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019dcf17-1b7e-72e0-8677-dc7cb68641dc" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019dcf17-021f-7423-8be9-0074aa8f2c7e" xlink:to="loc_srt_MinimumMember_019dcf17-1b7e-72e0-8677-dc7cb68641dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019dcf17-679a-7d63-8b27-65b733807110" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019dcf17-021f-7423-8be9-0074aa8f2c7e" xlink:to="loc_srt_MaximumMember_019dcf17-679a-7d63-8b27-65b733807110" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019dcf23-9e77-7517-b09d-78a15829ee8c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-7b93-803c-7bc2bb8393fe" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019dcf23-9e77-7517-b09d-78a15829ee8c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019dcf23-9e77-7517-b09d-78a15829ee8c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019dcf23-9e77-7517-b09d-78a15829ee8c" xlink:to="loc_us-gaap_SegmentDomain_019dcf23-9e77-7517-b09d-78a15829ee8c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019dcf23-9e77-798c-8d00-54e68981c8d9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019dcf23-9e77-7517-b09d-78a15829ee8c" xlink:to="loc_us-gaap_SegmentDomain_019dcf23-9e77-798c-8d00-54e68981c8d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateMember_019dcf23-9e77-7d75-bad1-3aca7b575123" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019dcf23-9e77-798c-8d00-54e68981c8d9" xlink:to="loc_us-gaap_CorporateMember_019dcf23-9e77-7d75-bad1-3aca7b575123" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Purchasepricebasedondefinitivesalesagreement_019cd2cc-7389-75c2-adb2-ffc8057e7f66" xlink:href="trs-20260331.xsd#trs_Purchasepricebasedondefinitivesalesagreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-75a2-9f0d-f605fdcf0df6" xlink:to="loc_trs_Purchasepricebasedondefinitivesalesagreement_019cd2cc-7389-75c2-adb2-ffc8057e7f66" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Proceedsonfinalizationofsaleofbusiness_019cd2cc-7389-7700-9bf1-a8b2811a0a35" xlink:href="trs-20260331.xsd#trs_Proceedsonfinalizationofsaleofbusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-75a2-9f0d-f605fdcf0df6" xlink:to="loc_trs_Proceedsonfinalizationofsaleofbusiness_019cd2cc-7389-7700-9bf1-a8b2811a0a35" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_019dcf00-4f73-7380-9c1b-a4df8ec57b84" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-75a2-9f0d-f605fdcf0df6" xlink:to="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_019dcf00-4f73-7380-9c1b-a4df8ec57b84" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_019dcf01-5304-7092-80b5-3c6d4f54b5bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-75a2-9f0d-f605fdcf0df6" xlink:to="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_019dcf01-5304-7092-80b5-3c6d4f54b5bf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentInterestRate_019dcf15-d305-731b-b029-f7a6dcd88114" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-75a2-9f0d-f605fdcf0df6" xlink:to="loc_us-gaap_InvestmentInterestRate_019dcf15-d305-731b-b029-f7a6dcd88114" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_MergersAcquisitionsDiligenceAndTransactionCosts_019dcf23-9e77-7fa7-83c9-f34d9ef96b67" xlink:href="trs-20260331.xsd#trs_MergersAcquisitionsDiligenceAndTransactionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-75a2-9f0d-f605fdcf0df6" xlink:to="loc_trs_MergersAcquisitionsDiligenceAndTransactionCosts_019dcf23-9e77-7fa7-83c9-f34d9ef96b67" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_019dcf25-6139-7bbd-a89b-51e666a63d0d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-75a2-9f0d-f605fdcf0df6" xlink:to="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_019dcf25-6139-7bbd-a89b-51e666a63d0d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested_019dcf49-c9ff-73ff-8487-3473d6204d72" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-75a2-9f0d-f605fdcf0df6" xlink:to="loc_us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested_019dcf49-c9ff-73ff-8487-3473d6204d72" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DiscontinuedOperationNetGainOnDispositionsOfAssets_019dd991-5d3c-7a0f-be28-3c49cb81248d" xlink:href="trs-20260331.xsd#trs_DiscontinuedOperationNetGainOnDispositionsOfAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-75a2-9f0d-f605fdcf0df6" xlink:to="loc_trs_DiscontinuedOperationNetGainOnDispositionsOfAssets_019dd991-5d3c-7a0f-be28-3c49cb81248d" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DiscontinuedOperationsResultsofDiscontinuedOperationsDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#DiscontinuedOperationsResultsofDiscontinuedOperationsDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DiscontinuedOperationsResultsofDiscontinuedOperationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-742d-a467-dc68fa06cdfd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-742d-a467-dc68fa06cdfd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7389-759f-b3d5-fa13ad80a1e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-742d-a467-dc68fa06cdfd" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7389-759f-b3d5-fa13ad80a1e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-759f-b3d5-fa13ad80a1e0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7389-759f-b3d5-fa13ad80a1e0" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-759f-b3d5-fa13ad80a1e0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-7f57-9178-9f13edb73794" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7389-759f-b3d5-fa13ad80a1e0" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-7f57-9178-9f13edb73794" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceReportableSegmentMember_019dcf09-8ae2-748f-9ac3-faba9c45d9d5" xlink:href="trs-20260331.xsd#trs_AerospaceReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-7f57-9178-9f13edb73794" xlink:to="loc_trs_AerospaceReportableSegmentMember_019dcf09-8ae2-748f-9ac3-faba9c45d9d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_019cd2cc-7389-73f5-8633-44089ad0c934" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-742d-a467-dc68fa06cdfd" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_019cd2cc-7389-73f5-8633-44089ad0c934" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019cd2cc-7389-73f5-8633-44089ad0c934_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019cd2cc-7389-73f5-8633-44089ad0c934" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019cd2cc-7389-73f5-8633-44089ad0c934_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019cd2cc-7389-7fe0-9857-884641e35d67" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019cd2cc-7389-73f5-8633-44089ad0c934" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019cd2cc-7389-7fe0-9857-884641e35d67" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_019cd2cc-7389-7623-88a8-e9cd7e8c93a8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationsDisposedOfBySaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_019cd2cc-7389-7fe0-9857-884641e35d67" xlink:to="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_019cd2cc-7389-7623-88a8-e9cd7e8c93a8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDiscontinuedOperationsMember_019dcf0b-4653-7c2e-92ba-3776af6000ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_019cd2cc-7389-7fe0-9857-884641e35d67" xlink:to="loc_us-gaap_SegmentDiscontinuedOperationsMember_019dcf0b-4653-7c2e-92ba-3776af6000ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet_019dcf06-b1b1-706b-b1a7-2ed27b26db3f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet_019dcf06-b1b1-706b-b1a7-2ed27b26db3f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInventoryCurrent_019dcf06-b1b1-7423-861a-88bfae95a128" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationInventoryCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInventoryCurrent_019dcf06-b1b1-7423-861a-88bfae95a128" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPrepaidAndOtherAssetsCurrent_019dcf06-b1b1-7b50-98af-99bafb652e53" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationPrepaidAndOtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPrepaidAndOtherAssetsCurrent_019dcf06-b1b1-7b50-98af-99bafb652e53" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_019dcf06-b1b1-712b-afac-c8ef0f784cc6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_019dcf06-b1b1-712b-afac-c8ef0f784cc6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent_019dcf06-b1b1-7cb0-ae1e-0f4d2f45f1c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent_019dcf06-b1b1-7cb0-ae1e-0f4d2f45f1c8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DisposalGroupIncludingDiscontinuedOperationOperatingLeaseRightOfUseAssets_019dcf06-b1b1-7548-8de0-287a208b59f4" xlink:href="trs-20260331.xsd#trs_DisposalGroupIncludingDiscontinuedOperationOperatingLeaseRightOfUseAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_trs_DisposalGroupIncludingDiscontinuedOperationOperatingLeaseRightOfUseAssets_019dcf06-b1b1-7548-8de0-287a208b59f4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwillNoncurrent_019dcf06-b1b1-70e7-978b-ab0635e96d78" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwillNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwillNoncurrent_019dcf06-b1b1-70e7-978b-ab0635e96d78" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsNoncurrent_019dcf06-b1b1-7110-828b-4f6f5ebe2c54" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsNoncurrent_019dcf06-b1b1-7110-828b-4f6f5ebe2c54" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets_019dcf06-b1b1-73d3-8599-ea7771933b45" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets_019dcf06-b1b1-73d3-8599-ea7771933b45" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation_019dcf06-b1b1-73df-a95b-e4b493a390cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation_019dcf06-b1b1-73df-a95b-e4b493a390cd" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayableCurrent_019dcf07-1cc5-7361-84dc-6a0daec32323" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayableCurrent_019dcf07-1cc5-7361-84dc-6a0daec32323" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccruedLiabilitiesCurrent_019dcf07-1cc5-7e9a-a3ca-10d90f4a7724" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccruedLiabilitiesCurrent_019dcf07-1cc5-7e9a-a3ca-10d90f4a7724" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DisposalGroupIncludingDiscontinuedOperationLeaseLiabilitiesCurrentPortion_019dcf07-1cc5-7c31-a2d9-3c2185d19eb6" xlink:href="trs-20260331.xsd#trs_DisposalGroupIncludingDiscontinuedOperationLeaseLiabilitiesCurrentPortion"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_trs_DisposalGroupIncludingDiscontinuedOperationLeaseLiabilitiesCurrentPortion_019dcf07-1cc5-7c31-a2d9-3c2185d19eb6" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_019dcf07-1cc5-75b7-98d7-191e8f912096" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_019dcf07-1cc5-75b7-98d7-191e8f912096" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DisposalGroupIncludingDiscontinuedOperationLeaseLiabilities_019dcf07-1cc5-7f1f-8b0f-dc4cdd2ce707" xlink:href="trs-20260331.xsd#trs_DisposalGroupIncludingDiscontinuedOperationLeaseLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_trs_DisposalGroupIncludingDiscontinuedOperationLeaseLiabilities_019dcf07-1cc5-7f1f-8b0f-dc4cdd2ce707" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilities_019dcf07-1cc5-7dcc-8788-4f861c5e2c1a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilities_019dcf07-1cc5-7dcc-8788-4f861c5e2c1a" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentLiabilities_019dcf07-1cc5-751f-9701-d5e74c9b7199" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentLiabilities_019dcf07-1cc5-751f-9701-d5e74c9b7199" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_019dcf07-1cc5-7eae-af8b-391109868961" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_019dcf07-1cc5-7eae-af8b-391109868961" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_019cd2cc-7389-7214-b36f-118eddf8659e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_019cd2cc-7389-7214-b36f-118eddf8659e" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold_019cd2cc-7389-7efa-aae4-d40717aabafd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold_019cd2cc-7389-7efa-aae4-d40717aabafd" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGrossProfitLoss_019cd2cc-7389-7a68-bceb-b14262d5902c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationGrossProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGrossProfitLoss_019cd2cc-7389-7a68-bceb-b14262d5902c" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DisposalGroupIncludingDiscontinuedOperationsSGA_019cd2cc-7389-73d7-8a92-6b597167af68" xlink:href="trs-20260331.xsd#trs_DisposalGroupIncludingDiscontinuedOperationsSGA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_trs_DisposalGroupIncludingDiscontinuedOperationsSGA_019cd2cc-7389-73d7-8a92-6b597167af68" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DiscontinuedOperationNetGainOnDispositionsOfAssets_019dcf08-6fe5-7a33-a570-38210fc336b5" xlink:href="trs-20260331.xsd#trs_DiscontinuedOperationNetGainOnDispositionsOfAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_trs_DiscontinuedOperationNetGainOnDispositionsOfAssets_019dcf08-6fe5-7a33-a570-38210fc336b5" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss_019cd2cc-7389-70ae-81c7-6241cee84928" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss_019cd2cc-7389-70ae-81c7-6241cee84928" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestExpense_019cd2cc-7389-7ef7-a2d0-047719eb0c59" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestExpense_019cd2cc-7389-7ef7-a2d0-047719eb0c59" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DisposalGroupIncludingDiscontinuedOperationsOtherExpenseNet_019cd2cc-7389-7053-bb61-48fac3af13fe" xlink:href="trs-20260331.xsd#trs_DisposalGroupIncludingDiscontinuedOperationsOtherExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_trs_DisposalGroupIncludingDiscontinuedOperationsOtherExpenseNet_019cd2cc-7389-7053-bb61-48fac3af13fe" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DisposalGroupIncludingDiscontinuedOperationsNonoperatingExpense_019cd2cc-7389-74bd-9f66-e4a90f1bab52" xlink:href="trs-20260331.xsd#trs_DisposalGroupIncludingDiscontinuedOperationsNonoperatingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_trs_DisposalGroupIncludingDiscontinuedOperationsNonoperatingExpense_019cd2cc-7389-74bd-9f66-e4a90f1bab52" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_019cd2cc-7389-7a15-8771-db700946797f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_019cd2cc-7389-7a15-8771-db700946797f" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_019cd2cc-7389-7ed4-9bc0-466d1336ffba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_019cd2cc-7389-7ed4-9bc0-466d1336ffba" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity_019cd2cc-7389-72b1-adfe-8df86d5a3d11" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity_019cd2cc-7389-72b1-adfe-8df86d5a3d11" xlink:type="arc" order="29"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_019dcf0b-e4ae-70ac-9490-ce3440572362" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_Depreciation_019dcf0b-e4ae-70ac-9490-ce3440572362" xlink:type="arc" order="30"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_019dcf0b-e4ae-7280-9772-d1f92d3532c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_019dcf0b-e4ae-7280-9772-d1f92d3532c7" xlink:type="arc" order="31"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_019dcf0c-2b09-7da2-a3c8-e01ce8e87879" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_ShareBasedCompensation_019dcf0c-2b09-7da2-a3c8-e01ce8e87879" xlink:type="arc" order="32"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDispositionOfAssets1_019dcf0c-8ba9-74a0-9618-6f54c941be2f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnDispositionOfAssets1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_GainLossOnDispositionOfAssets1_019dcf0c-8ba9-74a0-9618-6f54c941be2f" xlink:type="arc" order="33"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalExpenditureDiscontinuedOperations_019dcf0b-4653-7692-8be1-19530fac5583" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CapitalExpenditureDiscontinuedOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_CapitalExpenditureDiscontinuedOperations_019dcf0b-4653-7692-8be1-19530fac5583" xlink:type="arc" order="34"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019dcf0b-4653-7e30-b421-ef67dc8cc12f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019cd2cc-7389-73ec-83af-3d2a77497e1c" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019dcf0b-4653-7e30-b421-ef67dc8cc12f" xlink:type="arc" order="35"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/RevenueDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#RevenueDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/RevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019cd2cc-7389-70d6-9768-c6a0b18908d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019cd2cc-7389-7eae-849d-1f181de3e352" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019cd2cc-7389-70d6-9768-c6a0b18908d1" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019cd2cc-7389-7eae-849d-1f181de3e352" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019cd2cc-7389-7f11-b020-1751c09dcea7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019cd2cc-7389-7eae-849d-1f181de3e352" xlink:to="loc_srt_MajorCustomersAxis_019cd2cc-7389-7f11-b020-1751c09dcea7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019cd2cc-7389-7f11-b020-1751c09dcea7_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_019cd2cc-7389-7f11-b020-1751c09dcea7" xlink:to="loc_srt_NameOfMajorCustomerDomain_019cd2cc-7389-7f11-b020-1751c09dcea7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019cd2cc-7389-7c79-8759-f2db6a1f237e" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_019cd2cc-7389-7f11-b020-1751c09dcea7" xlink:to="loc_srt_NameOfMajorCustomerDomain_019cd2cc-7389-7c79-8759-f2db6a1f237e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ConsumercustomerendmarketMember_019cd2cc-7389-7650-ab9c-d4820592cb0e" xlink:href="trs-20260331.xsd#trs_ConsumercustomerendmarketMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019cd2cc-7389-7c79-8759-f2db6a1f237e" xlink:to="loc_trs_ConsumercustomerendmarketMember_019cd2cc-7389-7650-ab9c-d4820592cb0e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospacecustomerendmarketMember_019cd2cc-7389-7b83-99c7-512cc7f16a2b" xlink:href="trs-20260331.xsd#trs_AerospacecustomerendmarketMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019cd2cc-7389-7c79-8759-f2db6a1f237e" xlink:to="loc_trs_AerospacecustomerendmarketMember_019cd2cc-7389-7b83-99c7-512cc7f16a2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_IndustrialcustomerendmarketMember_019cd2cc-7389-7ca0-a2c8-1af064539d96" xlink:href="trs-20260331.xsd#trs_IndustrialcustomerendmarketMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019cd2cc-7389-7c79-8759-f2db6a1f237e" xlink:to="loc_trs_IndustrialcustomerendmarketMember_019cd2cc-7389-7ca0-a2c8-1af064539d96" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019cd2cc-7389-73d2-95d3-d36462a9a5a0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019cd2cc-7389-70d6-9768-c6a0b18908d1" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019cd2cc-7389-73d2-95d3-d36462a9a5a0" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/RevenueContractAssetsLiabilitiesDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#RevenueContractAssetsLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/RevenueContractAssetsLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRecognitionMilestoneMethodLineItems_019cf795-cc20-731c-9e90-64f983aebc2f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRecognitionMilestoneMethodLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredRevenueArrangementByTypeTable_019cf795-cc20-7e89-be1a-60e165a05ce5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredRevenueArrangementByTypeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRecognitionMilestoneMethodLineItems_019cf795-cc20-731c-9e90-64f983aebc2f" xlink:to="loc_us-gaap_DeferredRevenueArrangementByTypeTable_019cf795-cc20-7e89-be1a-60e165a05ce5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetGross_019cf795-cc20-74cc-a887-b3fedbc4b468" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerAssetGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRecognitionMilestoneMethodLineItems_019cf795-cc20-731c-9e90-64f983aebc2f" xlink:to="loc_us-gaap_ContractWithCustomerAssetGross_019cf795-cc20-74cc-a887-b3fedbc4b468" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_019cf795-cc20-7001-8ca3-2378e247136b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRecognitionMilestoneMethodLineItems_019cf795-cc20-731c-9e90-64f983aebc2f" xlink:to="loc_us-gaap_ContractWithCustomerLiability_019cf795-cc20-7001-8ca3-2378e247136b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_019cf797-0c06-76ff-9ffa-33adcbb417d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRecognitionMilestoneMethodLineItems_019cf795-cc20-731c-9e90-64f983aebc2f" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_019cf797-0c06-76ff-9ffa-33adcbb417d5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredRevenuePeriodIncreaseDecrease_019cf797-e6b2-7116-b954-f7e7d33d638f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredRevenuePeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRecognitionMilestoneMethodLineItems_019cf795-cc20-731c-9e90-64f983aebc2f" xlink:to="loc_us-gaap_DeferredRevenuePeriodIncreaseDecrease_019cf797-e6b2-7116-b954-f7e7d33d638f" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/RealignmentActionsDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#RealignmentActionsDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/RealignmentActionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentCostsLineItems_019cd2cc-7389-7012-b981-48cb5abd352b" xlink:href="trs-20260331.xsd#trs_RealignmentCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentActionsTable_019cd2cc-7389-7987-8b41-07471f0c4f3b" xlink:href="trs-20260331.xsd#trs_RealignmentActionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_trs_RealignmentCostsLineItems_019cd2cc-7389-7012-b981-48cb5abd352b" xlink:to="loc_trs_RealignmentActionsTable_019cd2cc-7389-7987-8b41-07471f0c4f3b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7389-789d-93b0-84c20b9eb172" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_RealignmentActionsTable_019cd2cc-7389-7987-8b41-07471f0c4f3b" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7389-789d-93b0-84c20b9eb172" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-789d-93b0-84c20b9eb172_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7389-789d-93b0-84c20b9eb172" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-789d-93b0-84c20b9eb172_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-720c-bb95-7ae65618e0b3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7389-789d-93b0-84c20b9eb172" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-720c-bb95-7ae65618e0b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_019cd2cc-7389-70db-9975-3638b26fbf05" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-720c-bb95-7ae65618e0b3" xlink:to="loc_us-gaap_CostOfSalesMember_019cd2cc-7389-70db-9975-3638b26fbf05" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_019cd2cc-7389-7a7c-9c4d-d408dbe16558" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-720c-bb95-7ae65618e0b3" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_019cd2cc-7389-7a7c-9c4d-d408dbe16558" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentActionsAxis_019cd2cc-7389-7c5c-86eb-b38470afeb31" xlink:href="trs-20260331.xsd#trs_RealignmentActionsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_RealignmentActionsTable_019cd2cc-7389-7987-8b41-07471f0c4f3b" xlink:to="loc_trs_RealignmentActionsAxis_019cd2cc-7389-7c5c-86eb-b38470afeb31" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentActionsDomain_019cd2cc-7389-7c5c-86eb-b38470afeb31_default" xlink:href="trs-20260331.xsd#trs_RealignmentActionsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_RealignmentActionsAxis_019cd2cc-7389-7c5c-86eb-b38470afeb31" xlink:to="loc_trs_RealignmentActionsDomain_019cd2cc-7389-7c5c-86eb-b38470afeb31_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentActionsDomain_019cd2cc-7389-7c45-a235-d884fdc53c41" xlink:href="trs-20260331.xsd#trs_RealignmentActionsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_RealignmentActionsAxis_019cd2cc-7389-7c5c-86eb-b38470afeb31" xlink:to="loc_trs_RealignmentActionsDomain_019cd2cc-7389-7c45-a235-d884fdc53c41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentActionsMember_019cd2cc-7389-7827-9046-99c4a46e7553" xlink:href="trs-20260331.xsd#trs_RealignmentActionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentActionsDomain_019cd2cc-7389-7c45-a235-d884fdc53c41" xlink:to="loc_trs_RealignmentActionsMember_019cd2cc-7389-7827-9046-99c4a46e7553" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Realignmentcosts_019cd2cc-7389-7984-be6e-e0ac89360c1f" xlink:href="trs-20260331.xsd#trs_Realignmentcosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019cd2cc-7389-7012-b981-48cb5abd352b" xlink:to="loc_trs_Realignmentcosts_019cd2cc-7389-7984-be6e-e0ac89360c1f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_FacilityConsolidationRealignmentCosts_019cd2cc-7389-79de-89fb-3f96ba0b0c68" xlink:href="trs-20260331.xsd#trs_FacilityConsolidationRealignmentCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019cd2cc-7389-7012-b981-48cb5abd352b" xlink:to="loc_trs_FacilityConsolidationRealignmentCosts_019cd2cc-7389-79de-89fb-3f96ba0b0c68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_EmployeeRelatedCosts_019cd2cc-7389-77d5-b944-aa7d9ad5b126" xlink:href="trs-20260331.xsd#trs_EmployeeRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019cd2cc-7389-7012-b981-48cb5abd352b" xlink:to="loc_trs_EmployeeRelatedCosts_019cd2cc-7389-77d5-b944-aa7d9ad5b126" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeveranceCosts1_019cd2cc-7389-7eed-8f9b-46551fef1487" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeveranceCosts1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019cd2cc-7389-7012-b981-48cb5abd352b" xlink:to="loc_us-gaap_SeveranceCosts1_019cd2cc-7389-7eed-8f9b-46551fef1487" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Cashpaidforseverance_019cd2cc-7389-7431-96d7-9939e88ebde4" xlink:href="trs-20260331.xsd#trs_Cashpaidforseverance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019cd2cc-7389-7012-b981-48cb5abd352b" xlink:to="loc_trs_Cashpaidforseverance_019cd2cc-7389-7431-96d7-9939e88ebde4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveAcceleratedDepreciation_019cd2cc-7389-7b03-96cd-bdc93730bb4c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserveAcceleratedDepreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019cd2cc-7389-7012-b981-48cb5abd352b" xlink:to="loc_us-gaap_RestructuringReserveAcceleratedDepreciation_019cd2cc-7389-7b03-96cd-bdc93730bb4c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryWriteDown_019cd2cc-7389-7e21-81f7-88a9935b27dc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InventoryWriteDown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019cd2cc-7389-7012-b981-48cb5abd352b" xlink:to="loc_us-gaap_InventoryWriteDown_019cd2cc-7389-7e21-81f7-88a9935b27dc" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_019cd2cc-7389-7a57-8896-91818341209c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019cd2cc-7389-7012-b981-48cb5abd352b" xlink:to="loc_us-gaap_ShareBasedCompensation_019cd2cc-7389-7a57-8896-91818341209c" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/AcquisitionsOtherAcquisitionsDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#AcquisitionsOtherAcquisitionsDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/AcquisitionsOtherAcquisitionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7edd-a2a9-884e73df1ff0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019cd2cc-7389-7c8b-9ade-75f9859ac24e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7edd-a2a9-884e73df1ff0" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019cd2cc-7389-7c8b-9ade-75f9859ac24e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019cd2cc-7389-737b-ae29-b90aa90154a8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019cd2cc-7389-7c8b-9ade-75f9859ac24e" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019cd2cc-7389-737b-ae29-b90aa90154a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd2cc-7389-737b-ae29-b90aa90154a8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019cd2cc-7389-737b-ae29-b90aa90154a8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd2cc-7389-737b-ae29-b90aa90154a8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd2cc-7389-7100-9cd0-126a2df83a0d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019cd2cc-7389-737b-ae29-b90aa90154a8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd2cc-7389-7100-9cd0-126a2df83a0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_WeldmacManufacturingCompanyMember_019cd2cc-7389-75ed-bed1-7a113e6eef74" xlink:href="trs-20260331.xsd#trs_WeldmacManufacturingCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd2cc-7389-7100-9cd0-126a2df83a0d" xlink:to="loc_trs_WeldmacManufacturingCompanyMember_019cd2cc-7389-75ed-bed1-7a113e6eef74" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_GMTAerospaceMember_019cd2cc-7389-7a25-9c79-62bf41529e32" xlink:href="trs-20260331.xsd#trs_GMTAerospaceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd2cc-7389-7100-9cd0-126a2df83a0d" xlink:to="loc_trs_GMTAerospaceMember_019cd2cc-7389-7a25-9c79-62bf41529e32" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019cd2cc-7389-7193-a6d9-b199e4451729" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7edd-a2a9-884e73df1ff0" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019cd2cc-7389-7193-a6d9-b199e4451729" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019cd2cc-7389-7f6c-ac08-75ceecb1a602" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7edd-a2a9-884e73df1ff0" xlink:to="loc_us-gaap_Goodwill_019cd2cc-7389-7f6c-ac08-75ceecb1a602" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_019cd2cc-7389-72a3-9484-47399679e602" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7edd-a2a9-884e73df1ff0" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_019cd2cc-7389-72a3-9484-47399679e602" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_BusinessCombinationRecognizedIdentifiableAssetsandLiabilitiesAssumedNetWorkingCapital_019cd2cc-7389-7c49-9438-1e77d9444dcd" xlink:href="trs-20260331.xsd#trs_BusinessCombinationRecognizedIdentifiableAssetsandLiabilitiesAssumedNetWorkingCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7edd-a2a9-884e73df1ff0" xlink:to="loc_trs_BusinessCombinationRecognizedIdentifiableAssetsandLiabilitiesAssumedNetWorkingCapital_019cd2cc-7389-7c49-9438-1e77d9444dcd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_019cd2cc-7389-7622-bcc3-1b68eb75d400" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7edd-a2a9-884e73df1ff0" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_019cd2cc-7389-7622-bcc3-1b68eb75d400" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_019cd2cc-7389-777b-b0d0-2612b05e43ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7edd-a2a9-884e73df1ff0" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_019cd2cc-7389-777b-b0d0-2612b05e43ab" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_019cd2cc-7389-7677-9fc9-91248b9faa5f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7edd-a2a9-884e73df1ff0" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_019cd2cc-7389-7677-9fc9-91248b9faa5f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueLow_019cd2cc-7389-7343-b661-41247b431b04" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueLow"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7edd-a2a9-884e73df1ff0" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueLow_019cd2cc-7389-7343-b661-41247b431b04" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_019cd2cc-7389-7933-b99e-ef2b9669ae30" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7edd-a2a9-884e73df1ff0" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_019cd2cc-7389-7933-b99e-ef2b9669ae30" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019cd2cc-7389-7ee3-bbed-910b8987c4b7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7edd-a2a9-884e73df1ff0" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019cd2cc-7389-7ee3-bbed-910b8987c4b7" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInTheRangeOfOutcomesContingentConsiderationLiabilityValueHigh_019cd2cc-7389-7a91-91dd-33b9d4ce928b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInTheRangeOfOutcomesContingentConsiderationLiabilityValueHigh"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7edd-a2a9-884e73df1ff0" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInTheRangeOfOutcomesContingentConsiderationLiabilityValueHigh_019cd2cc-7389-7a91-91dd-33b9d4ce928b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_019cd2cc-7389-730f-8718-45c0cf2ba88b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7edd-a2a9-884e73df1ff0" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_019cd2cc-7389-730f-8718-45c0cf2ba88b" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/AcquisitionsSaleofBusinessDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#AcquisitionsSaleofBusinessDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/AcquisitionsSaleofBusinessDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7cbd-b3a1-c05bf55f9936" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-7e9e-a900-a16bb196c8e5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7cbd-b3a1-c05bf55f9936" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-7e9e-a900-a16bb196c8e5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7389-7be5-9746-b3071116269c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019cd2cc-7389-7e9e-a900-a16bb196c8e5" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7389-7be5-9746-b3071116269c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-7be5-9746-b3071116269c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7389-7be5-9746-b3071116269c" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-7be5-9746-b3071116269c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-7dbe-b302-34fbdd8718a6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7389-7be5-9746-b3071116269c" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-7dbe-b302-34fbdd8718a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ArrowEngineMember_019cd2cc-7389-7e49-aa26-0fe1ac04063b" xlink:href="trs-20260331.xsd#trs_ArrowEngineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7389-7dbe-b302-34fbdd8718a6" xlink:to="loc_trs_ArrowEngineMember_019cd2cc-7389-7e49-aa26-0fe1ac04063b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_019cd2cc-7389-7127-bbd8-1c32d16d358a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7cbd-b3a1-c05bf55f9936" xlink:to="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_019cd2cc-7389-7127-bbd8-1c32d16d358a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_019cd2cc-7389-7d65-b95e-3060e2686757" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd2cc-7389-7cbd-b3a1-c05bf55f9936" xlink:to="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_019cd2cc-7389-7d65-b95e-3060e2686757" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsGoodwillNarrativeDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#GoodwillandOtherIntangibleAssetsGoodwillNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsGoodwillNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_019cd2cc-7389-7f3d-bbb1-856a3ca5382e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_019cd2cc-7389-72c2-b8e0-3bf305254898" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_019cd2cc-7389-7f3d-bbb1-856a3ca5382e" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_019cd2cc-7389-72c2-b8e0-3bf305254898" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_019cd2cc-7389-7022-bded-e7f24dbd33a8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019cd2cc-7389-72c2-b8e0-3bf305254898" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_019cd2cc-7389-7022-bded-e7f24dbd33a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_019cd2cc-7389-7022-bded-e7f24dbd33a8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_019cd2cc-7389-7022-bded-e7f24dbd33a8" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_019cd2cc-7389-7022-bded-e7f24dbd33a8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_019cd2cc-7389-7957-a3fc-ddf8ccfd9728" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_019cd2cc-7389-7022-bded-e7f24dbd33a8" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_019cd2cc-7389-7957-a3fc-ddf8ccfd9728" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputLongTermRevenueGrowthRateMember_019cd2cc-7389-73f5-a9e4-9b811e3477b5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputLongTermRevenueGrowthRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_019cd2cc-7389-7957-a3fc-ddf8ccfd9728" xlink:to="loc_us-gaap_MeasurementInputLongTermRevenueGrowthRateMember_019cd2cc-7389-73f5-a9e4-9b811e3477b5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_019cd2cc-7389-79ee-b9a7-d55e9794e682" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_019cd2cc-7389-7957-a3fc-ddf8ccfd9728" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_019cd2cc-7389-79ee-b9a7-d55e9794e682" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_QuantitativeImpairmentTestAxis_019cd2cc-7389-7adc-833f-42590dcbf69d" xlink:href="trs-20260331.xsd#trs_QuantitativeImpairmentTestAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019cd2cc-7389-72c2-b8e0-3bf305254898" xlink:to="loc_trs_QuantitativeImpairmentTestAxis_019cd2cc-7389-7adc-833f-42590dcbf69d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_QuantitativeImpairmentTestDomain_019cd2cc-7389-7adc-833f-42590dcbf69d_default" xlink:href="trs-20260331.xsd#trs_QuantitativeImpairmentTestDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_QuantitativeImpairmentTestAxis_019cd2cc-7389-7adc-833f-42590dcbf69d" xlink:to="loc_trs_QuantitativeImpairmentTestDomain_019cd2cc-7389-7adc-833f-42590dcbf69d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_QuantitativeImpairmentTestDomain_019cd2cc-7389-7bb6-a096-b018bd886549" xlink:href="trs-20260331.xsd#trs_QuantitativeImpairmentTestDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_QuantitativeImpairmentTestAxis_019cd2cc-7389-7adc-833f-42590dcbf69d" xlink:to="loc_trs_QuantitativeImpairmentTestDomain_019cd2cc-7389-7bb6-a096-b018bd886549" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillMember_019cd2cc-7389-761b-88c7-8ed5ffdeff56" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_QuantitativeImpairmentTestDomain_019cd2cc-7389-7bb6-a096-b018bd886549" xlink:to="loc_us-gaap_GoodwillMember_019cd2cc-7389-761b-88c7-8ed5ffdeff56" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7389-7836-bd1e-a72ca40845df" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019cd2cc-7389-72c2-b8e0-3bf305254898" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7389-7836-bd1e-a72ca40845df" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019cd2cc-7389-7836-bd1e-a72ca40845df_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7389-7836-bd1e-a72ca40845df" xlink:to="loc_us-gaap_SegmentDomain_019cd2cc-7389-7836-bd1e-a72ca40845df_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019cd2cc-7389-7982-b3ab-c28a524f3979" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7389-7836-bd1e-a72ca40845df" xlink:to="loc_us-gaap_SegmentDomain_019cd2cc-7389-7982-b3ab-c28a524f3979" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceReportableSegmentMember_019cd2cc-7389-72af-9610-b0862714b953" xlink:href="trs-20260331.xsd#trs_AerospaceReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019cd2cc-7389-7982-b3ab-c28a524f3979" xlink:to="loc_trs_AerospaceReportableSegmentMember_019cd2cc-7389-72af-9610-b0862714b953" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7389-74cb-91cf-a99a03872ff2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019cd2cc-7389-72c2-b8e0-3bf305254898" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7389-74cb-91cf-a99a03872ff2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-74cb-91cf-a99a03872ff2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7389-74cb-91cf-a99a03872ff2" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-74cb-91cf-a99a03872ff2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-7660-a990-6f5c4330ac2e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7389-74cb-91cf-a99a03872ff2" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-7660-a990-6f5c4330ac2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitAxis_019cd2cc-7389-78e1-a159-f173fc4b662f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReportingUnitAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019cd2cc-7389-72c2-b8e0-3bf305254898" xlink:to="loc_us-gaap_ReportingUnitAxis_019cd2cc-7389-78e1-a159-f173fc4b662f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_019cd2cc-7389-78e1-a159-f173fc4b662f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ReportingUnitAxis_019cd2cc-7389-78e1-a159-f173fc4b662f" xlink:to="loc_us-gaap_ReportingUnitDomain_019cd2cc-7389-78e1-a159-f173fc4b662f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_019cd2cc-7389-7c1c-8f25-e4a0c455fd70" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ReportingUnitAxis_019cd2cc-7389-78e1-a159-f173fc4b662f" xlink:to="loc_us-gaap_ReportingUnitDomain_019cd2cc-7389-7c1c-8f25-e4a0c455fd70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceFastenersReportingUnitMember_019cd2cc-7389-70bc-b0ed-a9431e6563f2" xlink:href="trs-20260331.xsd#trs_AerospaceFastenersReportingUnitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReportingUnitDomain_019cd2cc-7389-7c1c-8f25-e4a0c455fd70" xlink:to="loc_trs_AerospaceFastenersReportingUnitMember_019cd2cc-7389-70bc-b0ed-a9431e6563f2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceEngineeredProductsReportingUnitMember_019cd2cc-7389-73ee-a6d7-2f56c81c274c" xlink:href="trs-20260331.xsd#trs_AerospaceEngineeredProductsReportingUnitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReportingUnitDomain_019cd2cc-7389-7c1c-8f25-e4a0c455fd70" xlink:to="loc_trs_AerospaceEngineeredProductsReportingUnitMember_019cd2cc-7389-73ee-a6d7-2f56c81c274c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_FairValueInputsValuationMethodWeightingPercentageUsedMarketBasedApproach_019cd2cc-7389-7d92-9fad-a36bac6c9f7c" xlink:href="trs-20260331.xsd#trs_FairValueInputsValuationMethodWeightingPercentageUsedMarketBasedApproach"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019cd2cc-7389-7f3d-bbb1-856a3ca5382e" xlink:to="loc_trs_FairValueInputsValuationMethodWeightingPercentageUsedMarketBasedApproach_019cd2cc-7389-7d92-9fad-a36bac6c9f7c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_FairValueInputsValuationMethodWeightingPercentageUsedIncomeBasedApproach_019cd2cc-7389-757d-9246-419edad3b0b6" xlink:href="trs-20260331.xsd#trs_FairValueInputsValuationMethodWeightingPercentageUsedIncomeBasedApproach"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019cd2cc-7389-7f3d-bbb1-856a3ca5382e" xlink:to="loc_trs_FairValueInputsValuationMethodWeightingPercentageUsedIncomeBasedApproach_019cd2cc-7389-757d-9246-419edad3b0b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Fairvalueinputsvaluationmethoddiscountrate_019cd2cc-7389-7cfe-bdec-ae8b9bea7b36" xlink:href="trs-20260331.xsd#trs_Fairvalueinputsvaluationmethoddiscountrate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019cd2cc-7389-7f3d-bbb1-856a3ca5382e" xlink:to="loc_trs_Fairvalueinputsvaluationmethoddiscountrate_019cd2cc-7389-7cfe-bdec-ae8b9bea7b36" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Fairvalueinputsvaluationmethodresidualgrowthrate_019cd2cc-7389-7548-9cd1-1f2cdbcf26a9" xlink:href="trs-20260331.xsd#trs_Fairvalueinputsvaluationmethodresidualgrowthrate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019cd2cc-7389-7f3d-bbb1-856a3ca5382e" xlink:to="loc_trs_Fairvalueinputsvaluationmethodresidualgrowthrate_019cd2cc-7389-7548-9cd1-1f2cdbcf26a9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitPercentageOfFairValueInExcessOfCarryingAmount_019cd2cc-7389-7b7f-b09f-c4e5a2c11d33" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReportingUnitPercentageOfFairValueInExcessOfCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019cd2cc-7389-7f3d-bbb1-856a3ca5382e" xlink:to="loc_us-gaap_ReportingUnitPercentageOfFairValueInExcessOfCarryingAmount_019cd2cc-7389-7b7f-b09f-c4e5a2c11d33" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_019cd2cc-7389-7529-8064-18a212c60b2d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019cd2cc-7389-7f3d-bbb1-856a3ca5382e" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_019cd2cc-7389-7529-8064-18a212c60b2d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ChangeInDiscountRate_019cd2cc-7389-7cb5-8a88-fdf02ba16039" xlink:href="trs-20260331.xsd#trs_ChangeInDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019cd2cc-7389-7f3d-bbb1-856a3ca5382e" xlink:to="loc_trs_ChangeInDiscountRate_019cd2cc-7389-7cb5-8a88-fdf02ba16039" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ChangeInTerminalGrowthRate_019cd2cc-7389-7e64-81b0-3fe2e5b59590" xlink:href="trs-20260331.xsd#trs_ChangeInTerminalGrowthRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019cd2cc-7389-7f3d-bbb1-856a3ca5382e" xlink:to="loc_trs_ChangeInTerminalGrowthRate_019cd2cc-7389-7e64-81b0-3fe2e5b59590" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ChangeInGoodwillImpairmentDueToChangeInDiscountRate_019cd2cc-7389-7164-a5c5-4edb6941d9f6" xlink:href="trs-20260331.xsd#trs_ChangeInGoodwillImpairmentDueToChangeInDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019cd2cc-7389-7f3d-bbb1-856a3ca5382e" xlink:to="loc_trs_ChangeInGoodwillImpairmentDueToChangeInDiscountRate_019cd2cc-7389-7164-a5c5-4edb6941d9f6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ChangeInGoodwillImpairmentDueToChangeInTerminalRate_019cd2cc-7389-7976-9772-63c74f6a78ca" xlink:href="trs-20260331.xsd#trs_ChangeInGoodwillImpairmentDueToChangeInTerminalRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019cd2cc-7389-7f3d-bbb1-856a3ca5382e" xlink:to="loc_trs_ChangeInGoodwillImpairmentDueToChangeInTerminalRate_019cd2cc-7389-7976-9772-63c74f6a78ca" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsGoodwillRollforwardDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#GoodwillandOtherIntangibleAssetsGoodwillRollforwardDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsGoodwillRollforwardDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_019cd2cc-7389-7873-879b-b4c3898688ac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_019cd2cc-7389-7f29-b6e3-ff1ae3e9b410" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_019cd2cc-7389-7873-879b-b4c3898688ac" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_019cd2cc-7389-7f29-b6e3-ff1ae3e9b410" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7389-7f77-8914-acf25375473e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019cd2cc-7389-7f29-b6e3-ff1ae3e9b410" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7389-7f77-8914-acf25375473e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019cd2cc-7389-7f77-8914-acf25375473e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7389-7f77-8914-acf25375473e" xlink:to="loc_us-gaap_SegmentDomain_019cd2cc-7389-7f77-8914-acf25375473e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019cd2cc-7389-7cea-bbd6-6427ddc0fe83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7389-7f77-8914-acf25375473e" xlink:to="loc_us-gaap_SegmentDomain_019cd2cc-7389-7cea-bbd6-6427ddc0fe83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_PackagingReportableSegmentMember_019cd2cc-7389-770c-878b-dc7156aac6e8" xlink:href="trs-20260331.xsd#trs_PackagingReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019cd2cc-7389-7cea-bbd6-6427ddc0fe83" xlink:to="loc_trs_PackagingReportableSegmentMember_019cd2cc-7389-770c-878b-dc7156aac6e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceReportableSegmentMember_019cd2cc-7389-7f48-a805-214541dcf952" xlink:href="trs-20260331.xsd#trs_AerospaceReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019cd2cc-7389-7cea-bbd6-6427ddc0fe83" xlink:to="loc_trs_AerospaceReportableSegmentMember_019cd2cc-7389-7f48-a805-214541dcf952" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SpecialtyProductsReportableSegmentMember_019cd2cc-7389-7d62-a014-67810686eb58" xlink:href="trs-20260331.xsd#trs_SpecialtyProductsReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019cd2cc-7389-7cea-bbd6-6427ddc0fe83" xlink:to="loc_trs_SpecialtyProductsReportableSegmentMember_019cd2cc-7389-7d62-a014-67810686eb58" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillRollForward_019cd2cc-7389-7eff-b0db-a39af09576f2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019cd2cc-7389-7873-879b-b4c3898688ac" xlink:to="loc_us-gaap_GoodwillRollForward_019cd2cc-7389-7eff-b0db-a39af09576f2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019cd2cc-7389-7b79-bd4b-30b1d5fc2ef5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019cd2cc-7389-7eff-b0db-a39af09576f2" xlink:to="loc_us-gaap_Goodwill_019cd2cc-7389-7b79-bd4b-30b1d5fc2ef5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillAcquiredDuringPeriod_019cd2cc-7389-76cc-9068-05cae3ec59a6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillAcquiredDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019cd2cc-7389-7eff-b0db-a39af09576f2" xlink:to="loc_us-gaap_GoodwillAcquiredDuringPeriod_019cd2cc-7389-76cc-9068-05cae3ec59a6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Goodwillreassignedbetweensegments_019cd2cc-7389-7aa3-a709-db9a85eea160" xlink:href="trs-20260331.xsd#trs_Goodwillreassignedbetweensegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019cd2cc-7389-7eff-b0db-a39af09576f2" xlink:to="loc_trs_Goodwillreassignedbetweensegments_019cd2cc-7389-7aa3-a709-db9a85eea160" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_019cd2cc-7389-79f0-80ea-94ad5282e34c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019cd2cc-7389-7eff-b0db-a39af09576f2" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_019cd2cc-7389-79f0-80ea-94ad5282e34c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit_019cd2cc-7389-767c-a3c8-741d980fe0a9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019cd2cc-7389-7eff-b0db-a39af09576f2" xlink:to="loc_us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit_019cd2cc-7389-767c-a3c8-741d980fe0a9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments_019cd2cc-7389-7e78-a1d7-4287d281ab5a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019cd2cc-7389-7eff-b0db-a39af09576f2" xlink:to="loc_us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments_019cd2cc-7389-7e78-a1d7-4287d281ab5a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019cd2cc-7389-759b-a7e0-238637817948" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_019dc103-1a6d-774e-994a-1466682da6bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillImpairedAccumulatedImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019cd2cc-7389-7873-879b-b4c3898688ac" xlink:to="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_019dc103-1a6d-774e-994a-1466682da6bb" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsOtherIntangiblesNarrativeDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#GoodwillandOtherIntangibleAssetsOtherIntangiblesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsOtherIntangiblesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems_019cd2cc-7389-7b13-a6ca-6e4200013fd8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable_019cd2cc-7389-768c-9e4d-231ece064812" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems_019cd2cc-7389-7b13-a6ca-6e4200013fd8" xlink:to="loc_us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable_019cd2cc-7389-768c-9e4d-231ece064812" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019cd2cc-7389-7c4f-b7d9-6d63c0c7d52e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable_019cd2cc-7389-768c-9e4d-231ece064812" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019cd2cc-7389-7c4f-b7d9-6d63c0c7d52e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-7c4f-b7d9-6d63c0c7d52e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019cd2cc-7389-7c4f-b7d9-6d63c0c7d52e" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-7c4f-b7d9-6d63c0c7d52e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-7b60-b30d-1c74a3ef03af" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019cd2cc-7389-7c4f-b7d9-6d63c0c7d52e" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-7b60-b30d-1c74a3ef03af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_019cd2cc-7389-7a78-8751-ffc42f12bf97" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-7b60-b30d-1c74a3ef03af" xlink:to="loc_us-gaap_TradeNamesMember_019cd2cc-7389-7a78-8751-ffc42f12bf97" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7389-73e4-8689-d4819de8db6c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable_019cd2cc-7389-768c-9e4d-231ece064812" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7389-73e4-8689-d4819de8db6c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019cd2cc-7389-73e4-8689-d4819de8db6c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7389-73e4-8689-d4819de8db6c" xlink:to="loc_us-gaap_SegmentDomain_019cd2cc-7389-73e4-8689-d4819de8db6c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019cd2cc-7389-7261-8508-f99a1084e42f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7389-73e4-8689-d4819de8db6c" xlink:to="loc_us-gaap_SegmentDomain_019cd2cc-7389-7261-8508-f99a1084e42f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceReportableSegmentMember_019cd2cc-7389-721a-905f-76b0d9b0708b" xlink:href="trs-20260331.xsd#trs_AerospaceReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019cd2cc-7389-7261-8508-f99a1084e42f" xlink:to="loc_trs_AerospaceReportableSegmentMember_019cd2cc-7389-721a-905f-76b0d9b0708b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_019cd2cc-7389-7c49-8844-f129609ab0f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems_019cd2cc-7389-7b13-a6ca-6e4200013fd8" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_019cd2cc-7389-7c49-8844-f129609ab0f9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Fairvalueinputsvaluationmethoddiscountrate_019cd2cc-7389-7127-b16f-1ffefa87be07" xlink:href="trs-20260331.xsd#trs_Fairvalueinputsvaluationmethoddiscountrate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems_019cd2cc-7389-7b13-a6ca-6e4200013fd8" xlink:to="loc_trs_Fairvalueinputsvaluationmethoddiscountrate_019cd2cc-7389-7127-b16f-1ffefa87be07" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsScheduleofIntangibleAssetsexcludingGoodwillbyMajorClassDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#GoodwillandOtherIntangibleAssetsScheduleofIntangibleAssetsexcludingGoodwillbyMajorClassDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsScheduleofIntangibleAssetsexcludingGoodwillbyMajorClassDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_019cd2cc-7389-73f5-ba91-2c4b9b8f581b" xlink:href="trs-20260331.xsd#trs_IntangibleAssetsExcludingGoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_019cd2cc-7389-7d45-b46d-993d5d9cf92d" xlink:href="trs-20260331.xsd#trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_019cd2cc-7389-73f5-ba91-2c4b9b8f581b" xlink:to="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_019cd2cc-7389-7d45-b46d-993d5d9cf92d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019cd2cc-7389-73a7-9d4e-b5d8b919637e" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_019cd2cc-7389-7d45-b46d-993d5d9cf92d" xlink:to="loc_srt_RangeAxis_019cd2cc-7389-73a7-9d4e-b5d8b919637e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cd2cc-7389-73a7-9d4e-b5d8b919637e_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019cd2cc-7389-73a7-9d4e-b5d8b919637e" xlink:to="loc_srt_RangeMember_019cd2cc-7389-73a7-9d4e-b5d8b919637e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cd2cc-7389-75da-a25c-2efc332afc47" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019cd2cc-7389-73a7-9d4e-b5d8b919637e" xlink:to="loc_srt_RangeMember_019cd2cc-7389-75da-a25c-2efc332afc47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019cd2cc-7389-71d1-b26f-3af65585fd2d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cd2cc-7389-75da-a25c-2efc332afc47" xlink:to="loc_srt_MinimumMember_019cd2cc-7389-71d1-b26f-3af65585fd2d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019cd2cc-7389-79b5-a408-d67b17206f79" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cd2cc-7389-75da-a25c-2efc332afc47" xlink:to="loc_srt_MaximumMember_019cd2cc-7389-79b5-a408-d67b17206f79" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeAxis_019cd2cc-7389-70a7-a1ba-f5d20ad66e96" xlink:href="trs-20260331.xsd#trs_FiniteLivedIntangibleAssetsByUsefulLifeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_019cd2cc-7389-7d45-b46d-993d5d9cf92d" xlink:to="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeAxis_019cd2cc-7389-70a7-a1ba-f5d20ad66e96" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_019cd2cc-7389-70a7-a1ba-f5d20ad66e96_default" xlink:href="trs-20260331.xsd#trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeAxis_019cd2cc-7389-70a7-a1ba-f5d20ad66e96" xlink:to="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_019cd2cc-7389-70a7-a1ba-f5d20ad66e96_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_019cd2cc-7389-7c5e-91e6-2b35e1fd77da" xlink:href="trs-20260331.xsd#trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeAxis_019cd2cc-7389-70a7-a1ba-f5d20ad66e96" xlink:to="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_019cd2cc-7389-7c5e-91e6-2b35e1fd77da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_UsefulLifeFiveToTwelveYearsMember_019cd2cc-7389-7d6d-8610-85240e0b3dfd" xlink:href="trs-20260331.xsd#trs_UsefulLifeFiveToTwelveYearsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_019cd2cc-7389-7c5e-91e6-2b35e1fd77da" xlink:to="loc_trs_UsefulLifeFiveToTwelveYearsMember_019cd2cc-7389-7d6d-8610-85240e0b3dfd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_UsefulLifeFifteenToTwentyfiveYearsMember_019cd2cc-7389-7fa1-a6e4-9f9d263d1acc" xlink:href="trs-20260331.xsd#trs_UsefulLifeFifteenToTwentyfiveYearsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_019cd2cc-7389-7c5e-91e6-2b35e1fd77da" xlink:to="loc_trs_UsefulLifeFifteenToTwentyfiveYearsMember_019cd2cc-7389-7fa1-a6e4-9f9d263d1acc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_UsefulLifeOneToFifteenYearsMember_019cd2cc-7389-7ca3-bb51-4b87216ca1c1" xlink:href="trs-20260331.xsd#trs_UsefulLifeOneToFifteenYearsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_019cd2cc-7389-7c5e-91e6-2b35e1fd77da" xlink:to="loc_trs_UsefulLifeOneToFifteenYearsMember_019cd2cc-7389-7ca3-bb51-4b87216ca1c1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_UsefulLifeSeventeenToThirtyYearsMember_019cd2cc-7389-7a6d-8c27-7059d26306fc" xlink:href="trs-20260331.xsd#trs_UsefulLifeSeventeenToThirtyYearsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_019cd2cc-7389-7c5e-91e6-2b35e1fd77da" xlink:to="loc_trs_UsefulLifeSeventeenToThirtyYearsMember_019cd2cc-7389-7a6d-8c27-7059d26306fc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019cd2cc-7389-741e-869c-2eb074dd3a42" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_019cd2cc-7389-7d45-b46d-993d5d9cf92d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019cd2cc-7389-741e-869c-2eb074dd3a42" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-741e-869c-2eb074dd3a42_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019cd2cc-7389-741e-869c-2eb074dd3a42" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-741e-869c-2eb074dd3a42_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-7fd0-be94-ef1f3e4340a6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019cd2cc-7389-741e-869c-2eb074dd3a42" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-7fd0-be94-ef1f3e4340a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_019cd2cc-7389-7a69-bf29-68364e4f250f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-7fd0-be94-ef1f3e4340a6" xlink:to="loc_us-gaap_CustomerRelationshipsMember_019cd2cc-7389-7a69-bf29-68364e4f250f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_019cd2cc-7389-733d-a7c1-680f0687df31" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-7fd0-be94-ef1f3e4340a6" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_019cd2cc-7389-733d-a7c1-680f0687df31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019cd2cc-7389-764a-977c-9b4e8ddb8ab2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_019cd2cc-7389-7d45-b46d-993d5d9cf92d" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019cd2cc-7389-764a-977c-9b4e8ddb8ab2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-764a-977c-9b4e8ddb8ab2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019cd2cc-7389-764a-977c-9b4e8ddb8ab2" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-764a-977c-9b4e8ddb8ab2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-7910-b644-4a627d7eac06" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019cd2cc-7389-764a-977c-9b4e8ddb8ab2" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-7910-b644-4a627d7eac06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrademarksAndTradeNamesMember_019cd2cc-7389-756d-a707-bb4eca1bbd41" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TrademarksAndTradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-7910-b644-4a627d7eac06" xlink:to="loc_us-gaap_TrademarksAndTradeNamesMember_019cd2cc-7389-756d-a707-bb4eca1bbd41" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_019cd2cc-7389-7edf-969c-d9b304971637" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_019cd2cc-7389-73f5-ba91-2c4b9b8f581b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_019cd2cc-7389-7edf-969c-d9b304971637" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_019cd2cc-7389-72a3-9766-e277450e4eee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_019cd2cc-7389-73f5-ba91-2c4b9b8f581b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_019cd2cc-7389-72a3-9766-e277450e4eee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019cd2cc-7389-7251-93e1-c5b9a9897faf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_019cd2cc-7389-73f5-ba91-2c4b9b8f581b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019cd2cc-7389-7251-93e1-c5b9a9897faf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_019cd2cc-7389-7902-a524-53962a087181" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_019cd2cc-7389-73f5-ba91-2c4b9b8f581b" xlink:to="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_019cd2cc-7389-7902-a524-53962a087181" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_019cd2cc-7389-7b71-bdff-7968f8a2a7fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_019cd2cc-7389-73f5-ba91-2c4b9b8f581b" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_019cd2cc-7389-7b71-bdff-7968f8a2a7fe" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsAmortizationExpenseDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#GoodwillandOtherIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsAmortizationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsAmortizationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_trs_AmortizationOfIntangibleAssetsLineItems_019cd2cc-7389-76a6-9394-8c3eb8df9cdf" xlink:href="trs-20260331.xsd#trs_AmortizationOfIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_019cd2cc-7389-7f46-a7cc-d8ec78cf67f2" xlink:href="trs-20260331.xsd#trs_ScheduleOfAmortizationOfIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_trs_AmortizationOfIntangibleAssetsLineItems_019cd2cc-7389-76a6-9394-8c3eb8df9cdf" xlink:to="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_019cd2cc-7389-7f46-a7cc-d8ec78cf67f2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7389-7839-b105-c58feaef8d52" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_019cd2cc-7389-7f46-a7cc-d8ec78cf67f2" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7389-7839-b105-c58feaef8d52" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-7839-b105-c58feaef8d52_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7389-7839-b105-c58feaef8d52" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-7839-b105-c58feaef8d52_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-77a0-972e-6138c86b88a6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7389-7839-b105-c58feaef8d52" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-77a0-972e-6138c86b88a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_019cd2cc-7389-7172-ae76-1be323ae6500" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-77a0-972e-6138c86b88a6" xlink:to="loc_us-gaap_CostOfSalesMember_019cd2cc-7389-7172-ae76-1be323ae6500" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_019cd2cc-7389-70f7-bcd4-b25075bfd27f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-77a0-972e-6138c86b88a6" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_019cd2cc-7389-70f7-bcd4-b25075bfd27f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019cd2cc-7389-7997-996e-86c1a004543c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_019cd2cc-7389-7f46-a7cc-d8ec78cf67f2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019cd2cc-7389-7997-996e-86c1a004543c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-7997-996e-86c1a004543c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019cd2cc-7389-7997-996e-86c1a004543c" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-7997-996e-86c1a004543c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-73cc-83d2-6dff8bbefedc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019cd2cc-7389-7997-996e-86c1a004543c" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-73cc-83d2-6dff8bbefedc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_019cd2cc-7389-79c7-a100-800bbe873d4d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-73cc-83d2-6dff8bbefedc" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_019cd2cc-7389-79c7-a100-800bbe873d4d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_019cd2cc-7389-7222-acf3-eb8333ea70c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd2cc-7389-73cc-83d2-6dff8bbefedc" xlink:to="loc_us-gaap_CustomerRelationshipsMember_019cd2cc-7389-7222-acf3-eb8333ea70c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019dc102-b712-7482-80f2-c787b2df3440" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementOperatingActivitiesSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_019cd2cc-7389-7f46-a7cc-d8ec78cf67f2" xlink:to="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019dc102-b712-7482-80f2-c787b2df3440" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019dc102-b712-7482-80f2-c787b2df3440_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019dc102-b712-7482-80f2-c787b2df3440" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019dc102-b712-7482-80f2-c787b2df3440_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019dc102-b712-7dc3-923a-9e37a35cdb1d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019dc102-b712-7482-80f2-c787b2df3440" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019dc102-b712-7dc3-923a-9e37a35cdb1d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentContinuingOperationsMember_019dc102-b712-7541-aab1-01345f104630" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentContinuingOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentOperatingActivitiesDomain_019dc102-b712-7dc3-923a-9e37a35cdb1d" xlink:to="loc_us-gaap_SegmentContinuingOperationsMember_019dc102-b712-7541-aab1-01345f104630" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_019cd2cc-7389-7564-960e-65e63832f4c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_AmortizationOfIntangibleAssetsLineItems_019cd2cc-7389-76a6-9394-8c3eb8df9cdf" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_019cd2cc-7389-7564-960e-65e63832f4c3" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/PropertyandEquipmentNetPropertyandEquipmentTableDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#PropertyandEquipmentNetPropertyandEquipmentTableDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/PropertyandEquipmentNetPropertyandEquipmentTableDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019cd2cc-7389-73a9-8307-5c3926a2634c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019cd2cc-7389-779a-9229-35758c92c00c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019cd2cc-7389-73a9-8307-5c3926a2634c" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019cd2cc-7389-779a-9229-35758c92c00c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019cd2cc-7389-7594-a864-991d0901e765" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019cd2cc-7389-779a-9229-35758c92c00c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019cd2cc-7389-7594-a864-991d0901e765" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019cd2cc-7389-7594-a864-991d0901e765_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019cd2cc-7389-7594-a864-991d0901e765" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019cd2cc-7389-7594-a864-991d0901e765_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019cd2cc-7389-7a8d-bb04-df79a72401c1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019cd2cc-7389-7594-a864-991d0901e765" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019cd2cc-7389-7a8d-bb04-df79a72401c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandAndLandImprovementsMember_019cd2cc-7389-7bc4-a378-665ba041fbc7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LandAndLandImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019cd2cc-7389-7a8d-bb04-df79a72401c1" xlink:to="loc_us-gaap_LandAndLandImprovementsMember_019cd2cc-7389-7bc4-a378-665ba041fbc7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingMember_019cd2cc-7389-783d-bca9-0a60d135ba0c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019cd2cc-7389-7a8d-bb04-df79a72401c1" xlink:to="loc_us-gaap_BuildingMember_019cd2cc-7389-783d-bca9-0a60d135ba0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_019cd2cc-7389-71dd-9bec-359037531476" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019cd2cc-7389-7a8d-bb04-df79a72401c1" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_019cd2cc-7389-71dd-9bec-359037531476" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_019cd2cc-7389-7c2a-88be-5e15e1acccbd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019cd2cc-7389-73a9-8307-5c3926a2634c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_019cd2cc-7389-7c2a-88be-5e15e1acccbd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019cd2cc-7389-71eb-9984-3663d47a54e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019cd2cc-7389-73a9-8307-5c3926a2634c" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019cd2cc-7389-71eb-9984-3663d47a54e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019cd2cc-7389-7926-b1c4-915a1a96c5db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019cd2cc-7389-73a9-8307-5c3926a2634c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019cd2cc-7389-7926-b1c4-915a1a96c5db" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/PropertyandEquipmentNetDepreciationExpenseTableDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#PropertyandEquipmentNetDepreciationExpenseTableDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/PropertyandEquipmentNetDepreciationExpenseTableDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_trs_DepreciationExpenseLineItems_019cd2cc-7389-7722-b3bc-e8d4cfab2ce1" xlink:href="trs-20260331.xsd#trs_DepreciationExpenseLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ScheduleOfDepreciationExpenseTable_019cd2cc-7389-7756-a25c-513c6a079320" xlink:href="trs-20260331.xsd#trs_ScheduleOfDepreciationExpenseTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_trs_DepreciationExpenseLineItems_019cd2cc-7389-7722-b3bc-e8d4cfab2ce1" xlink:to="loc_trs_ScheduleOfDepreciationExpenseTable_019cd2cc-7389-7756-a25c-513c6a079320" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7389-7064-b23c-694328701b89" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDepreciationExpenseTable_019cd2cc-7389-7756-a25c-513c6a079320" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7389-7064-b23c-694328701b89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-7064-b23c-694328701b89_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7389-7064-b23c-694328701b89" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-7064-b23c-694328701b89_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-7bbe-8684-ca8fc19f7334" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7389-7064-b23c-694328701b89" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-7bbe-8684-ca8fc19f7334" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_019cd2cc-7389-775a-8184-cf922f8e4b79" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-7bbe-8684-ca8fc19f7334" xlink:to="loc_us-gaap_CostOfSalesMember_019cd2cc-7389-775a-8184-cf922f8e4b79" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_019cd2cc-7389-7950-8479-2b44e8a23cf6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7389-7bbe-8684-ca8fc19f7334" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_019cd2cc-7389-7950-8479-2b44e8a23cf6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019cd2cc-7389-7f7d-83da-4c82f65a810b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementOperatingActivitiesSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDepreciationExpenseTable_019cd2cc-7389-7756-a25c-513c6a079320" xlink:to="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019cd2cc-7389-7f7d-83da-4c82f65a810b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019cd2cc-7389-7f7d-83da-4c82f65a810b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019cd2cc-7389-7f7d-83da-4c82f65a810b" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019cd2cc-7389-7f7d-83da-4c82f65a810b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019cd2cc-7389-7735-beb3-7942081f77c0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019cd2cc-7389-7f7d-83da-4c82f65a810b" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019cd2cc-7389-7735-beb3-7942081f77c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentContinuingOperationsMember_019cd2cc-7389-7493-88c6-bf0e78f0f96a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentContinuingOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentOperatingActivitiesDomain_019cd2cc-7389-7735-beb3-7942081f77c0" xlink:to="loc_us-gaap_SegmentContinuingOperationsMember_019cd2cc-7389-7493-88c6-bf0e78f0f96a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_019cd2cc-7389-73aa-ab1d-e6e100749373" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DepreciationExpenseLineItems_019cd2cc-7389-7722-b3bc-e8d4cfab2ce1" xlink:to="loc_us-gaap_Depreciation_019cd2cc-7389-73aa-ab1d-e6e100749373" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/LongtermDebtDebtTableDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#LongtermDebtDebtTableDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/LongtermDebtDebtTableDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7e88-8e69-e92fd091bb82" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ScheduleOfDebtInstrumentsTable_019cd2cc-7459-708a-84ea-fdb37763959e" xlink:href="trs-20260331.xsd#trs_ScheduleOfDebtInstrumentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7e88-8e69-e92fd091bb82" xlink:to="loc_trs_ScheduleOfDebtInstrumentsTable_019cd2cc-7459-708a-84ea-fdb37763959e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-73cb-b683-c1e3b6cf7b4f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDebtInstrumentsTable_019cd2cc-7459-708a-84ea-fdb37763959e" xlink:to="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-73cb-b683-c1e3b6cf7b4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-73cb-b683-c1e3b6cf7b4f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-73cb-b683-c1e3b6cf7b4f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-73cb-b683-c1e3b6cf7b4f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-75eb-a84c-c0e2df0cacb3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-73cb-b683-c1e3b6cf7b4f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-75eb-a84c-c0e2df0cacb3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019cd2cc-7459-7f1c-9ecc-7bd772a4ce87" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-75eb-a84c-c0e2df0cacb3" xlink:to="loc_us-gaap_SeniorNotesMember_019cd2cc-7459-7f1c-9ecc-7bd772a4ce87" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_CreditAgreementMember_019cd2cc-7459-7431-bdc8-0be7cfa16467" xlink:href="trs-20260331.xsd#trs_CreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-75eb-a84c-c0e2df0cacb3" xlink:to="loc_trs_CreditAgreementMember_019cd2cc-7459-7431-bdc8-0be7cfa16467" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_A4.875SeniorUnsecuredNotesDue2025Member_019cd2cc-7459-7ee3-8a03-14b6dea15270" xlink:href="trs-20260331.xsd#trs_A4.875SeniorUnsecuredNotesDue2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-75eb-a84c-c0e2df0cacb3" xlink:to="loc_trs_A4.875SeniorUnsecuredNotesDue2025Member_019cd2cc-7459-7ee3-8a03-14b6dea15270" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_A4125SeniorUnsecuredNotesDue2029Member_019cd2cc-7459-7dcd-9ae7-84d5855a6ac6" xlink:href="trs-20260331.xsd#trs_A4125SeniorUnsecuredNotesDue2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-75eb-a84c-c0e2df0cacb3" xlink:to="loc_trs_A4125SeniorUnsecuredNotesDue2029Member_019cd2cc-7459-7dcd-9ae7-84d5855a6ac6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndCapitalLeaseObligations_019cd2cc-7459-72f7-9011-f9a28d10f9b4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7e88-8e69-e92fd091bb82" xlink:to="loc_us-gaap_DebtAndCapitalLeaseObligations_019cd2cc-7459-72f7-9011-f9a28d10f9b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_019cd2cc-7459-7c88-94e0-51aa3336efe2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7e88-8e69-e92fd091bb82" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_019cd2cc-7459-7c88-94e0-51aa3336efe2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_019cd2cc-7459-7f77-a745-7159dd92f296" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7e88-8e69-e92fd091bb82" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_019cd2cc-7459-7f77-a745-7159dd92f296" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/LongtermDebtSeniorNotesDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#LongtermDebtSeniorNotesDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/LongtermDebtSeniorNotesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7dea-b6ee-b3c1ae6b88d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-7ea2-bc08-480a91c7ca56" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7dea-b6ee-b3c1ae6b88d5" xlink:to="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-7ea2-bc08-480a91c7ca56" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019cd2cc-7459-7121-b7ac-729e1732c3d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-7ea2-bc08-480a91c7ca56" xlink:to="loc_us-gaap_CreditFacilityAxis_019cd2cc-7459-7121-b7ac-729e1732c3d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019cd2cc-7459-7121-b7ac-729e1732c3d3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019cd2cc-7459-7121-b7ac-729e1732c3d3" xlink:to="loc_us-gaap_CreditFacilityDomain_019cd2cc-7459-7121-b7ac-729e1732c3d3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019cd2cc-7459-7019-9a84-35de6e30d930" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019cd2cc-7459-7121-b7ac-729e1732c3d3" xlink:to="loc_us-gaap_CreditFacilityDomain_019cd2cc-7459-7019-9a84-35de6e30d930" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cd2cc-7459-7696-8f02-e882be9481f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-7ea2-bc08-480a91c7ca56" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cd2cc-7459-7696-8f02-e882be9481f9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-7696-8f02-e882be9481f9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cd2cc-7459-7696-8f02-e882be9481f9" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-7696-8f02-e882be9481f9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-7941-ba01-0f8d0312b1b3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cd2cc-7459-7696-8f02-e882be9481f9" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-7941-ba01-0f8d0312b1b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019cd2cc-7459-7a88-b2e1-2d3655918b7e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-7941-ba01-0f8d0312b1b3" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019cd2cc-7459-7a88-b2e1-2d3655918b7e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019cd2cc-7459-7dd5-8d6f-a80026515586" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-7ea2-bc08-480a91c7ca56" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019cd2cc-7459-7dd5-8d6f-a80026515586" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-7dd5-8d6f-a80026515586_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019cd2cc-7459-7dd5-8d6f-a80026515586" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-7dd5-8d6f-a80026515586_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-76ee-8e6d-0d7adeaaa0a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019cd2cc-7459-7dd5-8d6f-a80026515586" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-76ee-8e6d-0d7adeaaa0a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019cd2cc-7459-7662-8c9c-7f356c81b8dd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-76ee-8e6d-0d7adeaaa0a4" xlink:to="loc_us-gaap_SeniorNotesMember_019cd2cc-7459-7662-8c9c-7f356c81b8dd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-72d6-8d11-e6c7a6344272" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-7ea2-bc08-480a91c7ca56" xlink:to="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-72d6-8d11-e6c7a6344272" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-72d6-8d11-e6c7a6344272_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-72d6-8d11-e6c7a6344272" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-72d6-8d11-e6c7a6344272_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-724e-a75e-5f7ce8384ecf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-72d6-8d11-e6c7a6344272" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-724e-a75e-5f7ce8384ecf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_A4.875SeniorUnsecuredNotesDue2025Member_019cd2cc-7459-7b5e-a9c4-1c2f1dbf835b" xlink:href="trs-20260331.xsd#trs_A4.875SeniorUnsecuredNotesDue2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-724e-a75e-5f7ce8384ecf" xlink:to="loc_trs_A4.875SeniorUnsecuredNotesDue2025Member_019cd2cc-7459-7b5e-a9c4-1c2f1dbf835b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_A4125SeniorUnsecuredNotesDue2029Member_019cd2cc-7459-73ec-ae10-99d5e50dd1ae" xlink:href="trs-20260331.xsd#trs_A4125SeniorUnsecuredNotesDue2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-724e-a75e-5f7ce8384ecf" xlink:to="loc_trs_A4125SeniorUnsecuredNotesDue2029Member_019cd2cc-7459-73ec-ae10-99d5e50dd1ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_019cd2cc-7459-78ab-9530-9c09600e2d97" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-7ea2-bc08-480a91c7ca56" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_019cd2cc-7459-78ab-9530-9c09600e2d97" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019cd2cc-7459-78ab-9530-9c09600e2d97_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_019cd2cc-7459-78ab-9530-9c09600e2d97" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019cd2cc-7459-78ab-9530-9c09600e2d97_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019cd2cc-7459-7574-9978-16248743af1c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_019cd2cc-7459-78ab-9530-9c09600e2d97" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019cd2cc-7459-7574-9978-16248743af1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_019cd2cc-7459-7697-9076-b9d0957be0bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019cd2cc-7459-7574-9978-16248743af1c" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_019cd2cc-7459-7697-9076-b9d0957be0bb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_019cd2cc-7459-7b0e-862b-5e8489a829d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019cd2cc-7459-7574-9978-16248743af1c" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_019cd2cc-7459-7b0e-862b-5e8489a829d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodThreeMember_019cd2cc-7459-7c3f-a279-c26092f8fcc8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019cd2cc-7459-7574-9978-16248743af1c" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodThreeMember_019cd2cc-7459-7c3f-a279-c26092f8fcc8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodFourMember_019cd2cc-7459-72a8-8022-8730dcbf55de" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019cd2cc-7459-7574-9978-16248743af1c" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodFourMember_019cd2cc-7459-72a8-8022-8730dcbf55de" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019cd2cc-7459-791f-bec3-706471c97126" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7dea-b6ee-b3c1ae6b88d5" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019cd2cc-7459-791f-bec3-706471c97126" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019cd2cc-7459-7df2-92fd-d2e2f2a7ed90" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7dea-b6ee-b3c1ae6b88d5" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019cd2cc-7459-7df2-92fd-d2e2f2a7ed90" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentMaturityDate_019cd2cc-7459-7611-81d7-927a2fd678b2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentMaturityDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7dea-b6ee-b3c1ae6b88d5" xlink:to="loc_us-gaap_DebtInstrumentMaturityDate_019cd2cc-7459-7611-81d7-927a2fd678b2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfDebt_019cd2cc-7459-7fef-974c-c570b6853bf0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RepaymentsOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7dea-b6ee-b3c1ae6b88d5" xlink:to="loc_us-gaap_RepaymentsOfDebt_019cd2cc-7459-7fef-974c-c570b6853bf0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfFinancingCosts_019cd2cc-7459-716a-b093-8a6c670a3c9c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfFinancingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7dea-b6ee-b3c1ae6b88d5" xlink:to="loc_us-gaap_PaymentsOfFinancingCosts_019cd2cc-7459-716a-b093-8a6c670a3c9c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_019cd2cc-7459-7d90-897a-dc95da31853f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7dea-b6ee-b3c1ae6b88d5" xlink:to="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_019cd2cc-7459-7d90-897a-dc95da31853f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_019cd2cc-7459-7933-90c7-dc4b88fee351" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7dea-b6ee-b3c1ae6b88d5" xlink:to="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_019cd2cc-7459-7933-90c7-dc4b88fee351" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentDateOfFirstRequiredPayment1_019cd2cc-7459-76e1-9188-6eed11eb8bd8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentDateOfFirstRequiredPayment1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7dea-b6ee-b3c1ae6b88d5" xlink:to="loc_us-gaap_DebtInstrumentDateOfFirstRequiredPayment1_019cd2cc-7459-76e1-9188-6eed11eb8bd8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Percentageofprincipalthatcanberedeemedwithcashproceedsfromanequityoffering_019cd2cc-7459-7505-95c4-7d03941a2304" xlink:href="trs-20260331.xsd#trs_Percentageofprincipalthatcanberedeemedwithcashproceedsfromanequityoffering"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7dea-b6ee-b3c1ae6b88d5" xlink:to="loc_trs_Percentageofprincipalthatcanberedeemedwithcashproceedsfromanequityoffering_019cd2cc-7459-7505-95c4-7d03941a2304" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Debtinstrumentredemptionpricewithnetproceedsfromequityoffering_019cd2cc-7459-7668-9d03-4f6bd0493a4d" xlink:href="trs-20260331.xsd#trs_Debtinstrumentredemptionpricewithnetproceedsfromequityoffering"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7dea-b6ee-b3c1ae6b88d5" xlink:to="loc_trs_Debtinstrumentredemptionpricewithnetproceedsfromequityoffering_019cd2cc-7459-7668-9d03-4f6bd0493a4d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_019cd2cc-7459-7798-8d40-3496ca16ceae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7dea-b6ee-b3c1ae6b88d5" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_019cd2cc-7459-7798-8d40-3496ca16ceae" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarlyRepaymentOfSeniorDebt_019cd2cc-7459-7648-828c-368aa3dbf776" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarlyRepaymentOfSeniorDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7dea-b6ee-b3c1ae6b88d5" xlink:to="loc_us-gaap_EarlyRepaymentOfSeniorDebt_019cd2cc-7459-7648-828c-368aa3dbf776" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFeeAmount_019cd2cc-7459-725b-8254-f451fe15305f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFeeAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7dea-b6ee-b3c1ae6b88d5" xlink:to="loc_us-gaap_DebtInstrumentFeeAmount_019cd2cc-7459-725b-8254-f451fe15305f" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFee_019cd2cc-7459-7fbb-ac02-d39f32c80f78" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFee"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7dea-b6ee-b3c1ae6b88d5" xlink:to="loc_us-gaap_DebtInstrumentFee_019cd2cc-7459-7fbb-ac02-d39f32c80f78" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AccruedInterestPaidThroughRedemptionDate_019cd2cc-7459-7cbf-84d9-0399c725ad7d" xlink:href="trs-20260331.xsd#trs_AccruedInterestPaidThroughRedemptionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7dea-b6ee-b3c1ae6b88d5" xlink:to="loc_trs_AccruedInterestPaidThroughRedemptionDate_019cd2cc-7459-7cbf-84d9-0399c725ad7d" xlink:type="arc" order="14"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/LongtermDebtCreditAgreementDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#LongtermDebtCreditAgreementDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/LongtermDebtCreditAgreementDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-707d-9b35-2bc90f16b7d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-707d-9b35-2bc90f16b7d5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-7ed3-a2a4-eacbc9592893" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-707d-9b35-2bc90f16b7d5" xlink:to="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-7ed3-a2a4-eacbc9592893" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7ed3-a2a4-eacbc9592893_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-7ed3-a2a4-eacbc9592893" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7ed3-a2a4-eacbc9592893_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7326-883f-8b6a7258f8a7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-7ed3-a2a4-eacbc9592893" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7326-883f-8b6a7258f8a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_BankdebtandreceivablesfacilityMember_019cd2cc-7459-706f-9f5e-22e93b4239ad" xlink:href="trs-20260331.xsd#trs_BankdebtandreceivablesfacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7326-883f-8b6a7258f8a7" xlink:to="loc_trs_BankdebtandreceivablesfacilityMember_019cd2cc-7459-706f-9f5e-22e93b4239ad" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RevolvingCreditAndTermLoanFacilitiesMember_019cd2cc-7459-713a-8137-93a062aa8005" xlink:href="trs-20260331.xsd#trs_RevolvingCreditAndTermLoanFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7326-883f-8b6a7258f8a7" xlink:to="loc_trs_RevolvingCreditAndTermLoanFacilitiesMember_019cd2cc-7459-713a-8137-93a062aa8005" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019cd2cc-7459-7606-b576-f4a634302849" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7326-883f-8b6a7258f8a7" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019cd2cc-7459-7606-b576-f4a634302849" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cd2cc-7459-784b-8aba-7e4ce9ff3a99" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-707d-9b35-2bc90f16b7d5" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cd2cc-7459-784b-8aba-7e4ce9ff3a99" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-784b-8aba-7e4ce9ff3a99_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cd2cc-7459-784b-8aba-7e4ce9ff3a99" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-784b-8aba-7e4ce9ff3a99_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-74a4-8497-6a53a6df4201" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cd2cc-7459-784b-8aba-7e4ce9ff3a99" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-74a4-8497-6a53a6df4201" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019cd2cc-7459-7c17-bec2-4cb0e3b74922" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-74a4-8497-6a53a6df4201" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019cd2cc-7459-7c17-bec2-4cb0e3b74922" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019cd2cc-7459-7186-8777-bf35c484c62d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-707d-9b35-2bc90f16b7d5" xlink:to="loc_us-gaap_CreditFacilityAxis_019cd2cc-7459-7186-8777-bf35c484c62d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019cd2cc-7459-7186-8777-bf35c484c62d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019cd2cc-7459-7186-8777-bf35c484c62d" xlink:to="loc_us-gaap_CreditFacilityDomain_019cd2cc-7459-7186-8777-bf35c484c62d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019cd2cc-7459-7031-96e1-70b98beb5ce2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019cd2cc-7459-7186-8777-bf35c484c62d" xlink:to="loc_us-gaap_CreditFacilityDomain_019cd2cc-7459-7031-96e1-70b98beb5ce2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_TermloanAfacilityMember_019cd2cc-7459-71f2-9de7-247297ed451e" xlink:href="trs-20260331.xsd#trs_TermloanAfacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019cd2cc-7459-7031-96e1-70b98beb5ce2" xlink:to="loc_trs_TermloanAfacilityMember_019cd2cc-7459-71f2-9de7-247297ed451e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019cd2cc-7459-7e53-bdee-406d5822903c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019cd2cc-7459-7031-96e1-70b98beb5ce2" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019cd2cc-7459-7e53-bdee-406d5822903c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_019cd2cc-7459-746f-96ff-c80c2aceb752" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019cd2cc-7459-7031-96e1-70b98beb5ce2" xlink:to="loc_us-gaap_LetterOfCreditMember_019cd2cc-7459-746f-96ff-c80c2aceb752" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019cd2cc-7459-7758-b1b5-e9f4653d6003" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-707d-9b35-2bc90f16b7d5" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019cd2cc-7459-7758-b1b5-e9f4653d6003" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-7758-b1b5-e9f4653d6003_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019cd2cc-7459-7758-b1b5-e9f4653d6003" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-7758-b1b5-e9f4653d6003_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-75c8-8cfa-de44eb6768f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019cd2cc-7459-7758-b1b5-e9f4653d6003" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-75c8-8cfa-de44eb6768f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019cd2cc-7459-724a-b9e6-9cf4202826f2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-75c8-8cfa-de44eb6768f9" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019cd2cc-7459-724a-b9e6-9cf4202826f2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SeniorSecuredTermLoanMember_019cd2cc-7459-7b70-8d36-f2265af8fe86" xlink:href="trs-20260331.xsd#trs_SeniorSecuredTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-75c8-8cfa-de44eb6768f9" xlink:to="loc_trs_SeniorSecuredTermLoanMember_019cd2cc-7459-7b70-8d36-f2265af8fe86" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicDistributionAxis_019cd2cc-7459-7a21-ac16-3d0587f93915" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeographicDistributionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-707d-9b35-2bc90f16b7d5" xlink:to="loc_us-gaap_GeographicDistributionAxis_019cd2cc-7459-7a21-ac16-3d0587f93915" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicDistributionDomain_019cd2cc-7459-7a21-ac16-3d0587f93915_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeographicDistributionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GeographicDistributionAxis_019cd2cc-7459-7a21-ac16-3d0587f93915" xlink:to="loc_us-gaap_GeographicDistributionDomain_019cd2cc-7459-7a21-ac16-3d0587f93915_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicDistributionDomain_019cd2cc-7459-7867-a17d-2b6732c26278" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeographicDistributionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GeographicDistributionAxis_019cd2cc-7459-7a21-ac16-3d0587f93915" xlink:to="loc_us-gaap_GeographicDistributionDomain_019cd2cc-7459-7867-a17d-2b6732c26278" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicDistributionForeignMember_019cd2cc-7459-7917-a7ce-3fbffa2cbafc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeographicDistributionForeignMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GeographicDistributionDomain_019cd2cc-7459-7867-a17d-2b6732c26278" xlink:to="loc_us-gaap_GeographicDistributionForeignMember_019cd2cc-7459-7917-a7ce-3fbffa2cbafc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicDistributionDomesticMember_019cd2cc-7459-788c-84e3-3c4cd4dd0570" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeographicDistributionDomesticMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GeographicDistributionDomain_019cd2cc-7459-7867-a17d-2b6732c26278" xlink:to="loc_us-gaap_GeographicDistributionDomesticMember_019cd2cc-7459-788c-84e3-3c4cd4dd0570" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019cd2cc-7459-7635-b6ba-5ff1899ea738" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-707d-9b35-2bc90f16b7d5" xlink:to="loc_srt_RangeAxis_019cd2cc-7459-7635-b6ba-5ff1899ea738" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cd2cc-7459-7635-b6ba-5ff1899ea738_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019cd2cc-7459-7635-b6ba-5ff1899ea738" xlink:to="loc_srt_RangeMember_019cd2cc-7459-7635-b6ba-5ff1899ea738_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cd2cc-7459-7778-94af-b6eb907b83e5" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019cd2cc-7459-7635-b6ba-5ff1899ea738" xlink:to="loc_srt_RangeMember_019cd2cc-7459-7778-94af-b6eb907b83e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019cd2cc-7459-72ad-a9b8-145bd01f8dfe" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cd2cc-7459-7778-94af-b6eb907b83e5" xlink:to="loc_srt_MinimumMember_019cd2cc-7459-72ad-a9b8-145bd01f8dfe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019cd2cc-7459-7cee-9e37-727ad1a51652" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cd2cc-7459-7778-94af-b6eb907b83e5" xlink:to="loc_srt_MaximumMember_019cd2cc-7459-7cee-9e37-727ad1a51652" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfFinancingCosts_019cd2cc-7459-79a5-9e6f-bc63ddee7d10" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfFinancingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_us-gaap_PaymentsOfFinancingCosts_019cd2cc-7459-79a5-9e6f-bc63ddee7d10" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_019cd2cc-7459-7179-a7c8-e60d4d24d256" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_019cd2cc-7459-7179-a7c8-e60d4d24d256" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_019cd2cc-7459-74fe-9bf8-b4ca7e605d36" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_019cd2cc-7459-74fe-9bf8-b4ca7e605d36" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_019cd2cc-7459-7025-a6ff-b046331052a3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WriteOffOfDeferredDebtIssuanceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_019cd2cc-7459-7025-a6ff-b046331052a3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases_019cd2cc-7459-7a03-9047-a8626ae7121f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases_019cd2cc-7459-7a03-9047-a8626ae7121f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019cd2cc-7459-7a2d-8640-5b5814748181" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019cd2cc-7459-7a2d-8640-5b5814748181" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentMaturityDate_019cd2cc-7459-7c2c-9b2d-95c9859c2b4c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentMaturityDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_us-gaap_DebtInstrumentMaturityDate_019cd2cc-7459-7c2c-9b2d-95c9859c2b4c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019cd2cc-7459-7c06-be0a-0fb6c059dce6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019cd2cc-7459-7c06-be0a-0fb6c059dce6" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019cd2cc-7459-7ff5-b993-ad4373adcb63" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019cd2cc-7459-7ff5-b993-ad4373adcb63" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_IncrementalDebtCommitmentsCapacity_019cd2cc-7459-754f-bb31-9cbb22f73e6e" xlink:href="trs-20260331.xsd#trs_IncrementalDebtCommitmentsCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_trs_IncrementalDebtCommitmentsCapacity_019cd2cc-7459-754f-bb31-9cbb22f73e6e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_NetLeverageRatio_019cd2cc-7459-7368-89e3-3d4cff592d40" xlink:href="trs-20260331.xsd#trs_NetLeverageRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_trs_NetLeverageRatio_019cd2cc-7459-7368-89e3-3d4cff592d40" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LetterOfCreditMaximumBorrowingCapacity_019cd2cc-7459-7c9f-bb6c-0140b16cb956" xlink:href="trs-20260331.xsd#trs_LetterOfCreditMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_trs_LetterOfCreditMaximumBorrowingCapacity_019cd2cc-7459-7c9f-bb6c-0140b16cb956" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_019cd2cc-7459-7730-aa0f-78a277c42c31" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_us-gaap_LineOfCredit_019cd2cc-7459-7730-aa0f-78a277c42c31" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019cd2cc-7459-793e-8aa0-c9534d960112" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019cd2cc-7459-793e-8aa0-c9534d960112" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_019cd2cc-7459-7d94-a7b3-e64826a68932" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_019cd2cc-7459-7d94-a7b3-e64826a68932" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_019cd2cc-7459-7a8a-8cec-3c5bea1cd5a3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_019cd2cc-7459-7a8a-8cec-3c5bea1cd5a3" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LongTermDebtFairValueOfParValue_019cd2cc-7459-7f9f-b02a-68c9a363eb60" xlink:href="trs-20260331.xsd#trs_LongTermDebtFairValueOfParValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_trs_LongTermDebtFairValueOfParValue_019cd2cc-7459-7f9f-b02a-68c9a363eb60" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LineOfCreditBorrowingCapacityConsideringCovenantRestrictions_019cd2cc-7459-795d-b319-f97099bcf5a0" xlink:href="trs-20260331.xsd#trs_LineOfCreditBorrowingCapacityConsideringCovenantRestrictions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_trs_LineOfCreditBorrowingCapacityConsideringCovenantRestrictions_019cd2cc-7459-795d-b319-f97099bcf5a0" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_019cd2cc-7459-77dc-9958-5b3a7d23ccc0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfDebtExtinguishmentCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_019cd2cc-7459-77dc-9958-5b3a7d23ccc0" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsGross_019cd2cc-7459-7581-8d66-e570a0fc9525" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFinanceCostsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_us-gaap_DeferredFinanceCostsGross_019cd2cc-7459-7581-8d66-e570a0fc9525" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtIssuanceCosts_019cd2cc-7459-75f0-b4c9-ede747e48825" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfDebtIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7d4c-b161-968078962bf1" xlink:to="loc_us-gaap_PaymentsOfDebtIssuanceCosts_019cd2cc-7459-75f0-b4c9-ede747e48825" xlink:type="arc" order="20"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/LongtermDebtReceivablesFacilityDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#LongtermDebtReceivablesFacilityDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/LongtermDebtReceivablesFacilityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7bd5-a834-ee98d7ee82f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-7855-bd85-2fa01270dc1a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7bd5-a834-ee98d7ee82f4" xlink:to="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-7855-bd85-2fa01270dc1a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019cd2cc-7459-7aef-9df7-93f4db771333" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-7855-bd85-2fa01270dc1a" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019cd2cc-7459-7aef-9df7-93f4db771333" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-7aef-9df7-93f4db771333_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019cd2cc-7459-7aef-9df7-93f4db771333" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-7aef-9df7-93f4db771333_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-7331-b3ce-94ba35ba57a5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019cd2cc-7459-7aef-9df7-93f4db771333" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-7331-b3ce-94ba35ba57a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_019cd2cc-7459-7b32-96a3-c767195707d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-7331-b3ce-94ba35ba57a5" xlink:to="loc_us-gaap_SecuredDebtMember_019cd2cc-7459-7b32-96a3-c767195707d3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SecuredDebtMaximumBorrowingCapacity_019cd2cc-7459-73f6-8a25-7cc74875fdf3" xlink:href="trs-20260331.xsd#trs_SecuredDebtMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7bd5-a834-ee98d7ee82f4" xlink:to="loc_trs_SecuredDebtMaximumBorrowingCapacity_019cd2cc-7459-73f6-8a25-7cc74875fdf3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019cd2cc-7459-75b6-8f8f-6fea0040c701" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7bd5-a834-ee98d7ee82f4" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019cd2cc-7459-75b6-8f8f-6fea0040c701" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DebtInstrumentUnusedBorrowingCapacityFeePercentage_019cd2cc-7459-7cb1-9d59-04d8254bd938" xlink:href="trs-20260331.xsd#trs_DebtInstrumentUnusedBorrowingCapacityFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7bd5-a834-ee98d7ee82f4" xlink:to="loc_trs_DebtInstrumentUnusedBorrowingCapacityFeePercentage_019cd2cc-7459-7cb1-9d59-04d8254bd938" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebt_019cd2cc-7459-7bc4-b5e6-4ae120347514" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SecuredDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7bd5-a834-ee98d7ee82f4" xlink:to="loc_us-gaap_SecuredDebt_019cd2cc-7459-7bc4-b5e6-4ae120347514" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_019cd2cc-7459-72c1-8e4d-91990d083e9f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7bd5-a834-ee98d7ee82f4" xlink:to="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_019cd2cc-7459-72c1-8e4d-91990d083e9f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ReceivablesFacililtyDebtAggregateCosts_019cd2cc-7459-76c1-bd27-32800409ac65" xlink:href="trs-20260331.xsd#trs_ReceivablesFacililtyDebtAggregateCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7bd5-a834-ee98d7ee82f4" xlink:to="loc_trs_ReceivablesFacililtyDebtAggregateCosts_019cd2cc-7459-76c1-bd27-32800409ac65" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentMaturityDate_019cd2cc-7459-7a75-b95c-50b1038aef05" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentMaturityDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7bd5-a834-ee98d7ee82f4" xlink:to="loc_us-gaap_DebtInstrumentMaturityDate_019cd2cc-7459-7a75-b95c-50b1038aef05" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AverageDiscountRateReceivablesFacility_019cd2cc-7459-719f-906b-b97ce690e8dd" xlink:href="trs-20260331.xsd#trs_AverageDiscountRateReceivablesFacility"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-7bd5-a834-ee98d7ee82f4" xlink:to="loc_trs_AverageDiscountRateReceivablesFacility_019cd2cc-7459-719f-906b-b97ce690e8dd" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/OtherRevolvingLoanFacilityDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#OtherRevolvingLoanFacilityDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/OtherRevolvingLoanFacilityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-748a-9014-a54ca55fda34" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-76b8-a666-0fb752954a91" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-748a-9014-a54ca55fda34" xlink:to="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-76b8-a666-0fb752954a91" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019cd2cc-7459-7300-9402-c3a96ca94c16" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-76b8-a666-0fb752954a91" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019cd2cc-7459-7300-9402-c3a96ca94c16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-7300-9402-c3a96ca94c16_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019cd2cc-7459-7300-9402-c3a96ca94c16" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-7300-9402-c3a96ca94c16_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-7524-b8b5-e46059890153" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019cd2cc-7459-7300-9402-c3a96ca94c16" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-7524-b8b5-e46059890153" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019cd2cc-7459-7268-96d2-52177dd8f5ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019cd2cc-7459-7524-b8b5-e46059890153" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019cd2cc-7459-7268-96d2-52177dd8f5ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-736d-8b00-34d9f0a4319f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019cd2cc-7459-76b8-a666-0fb752954a91" xlink:to="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-736d-8b00-34d9f0a4319f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-736d-8b00-34d9f0a4319f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-736d-8b00-34d9f0a4319f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-736d-8b00-34d9f0a4319f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-721a-bb35-30969fe6aeea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-736d-8b00-34d9f0a4319f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-721a-bb35-30969fe6aeea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_019cd2cc-7459-7a45-a436-f261666d6ef3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NonUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-721a-bb35-30969fe6aeea" xlink:to="loc_us-gaap_NonUsMember_019cd2cc-7459-7a45-a436-f261666d6ef3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019cd2cc-7459-7f18-965d-544e6afcde62" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-748a-9014-a54ca55fda34" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019cd2cc-7459-7f18-965d-544e6afcde62" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_019cd2cc-7459-7d66-909c-015c3c6cc71a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-748a-9014-a54ca55fda34" xlink:to="loc_us-gaap_LineOfCredit_019cd2cc-7459-7d66-909c-015c3c6cc71a" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/LongtermDebtFairValueDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#LongtermDebtFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/LongtermDebtFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-72de-9f7b-1da8be66840f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ScheduleOfDebtInstrumentsTable_019cd2cc-7459-7b79-a29d-106b074b34ba" xlink:href="trs-20260331.xsd#trs_ScheduleOfDebtInstrumentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-72de-9f7b-1da8be66840f" xlink:to="loc_trs_ScheduleOfDebtInstrumentsTable_019cd2cc-7459-7b79-a29d-106b074b34ba" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cd2cc-7459-7040-9b20-da93da20d993" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDebtInstrumentsTable_019cd2cc-7459-7b79-a29d-106b074b34ba" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cd2cc-7459-7040-9b20-da93da20d993" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-7040-9b20-da93da20d993_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cd2cc-7459-7040-9b20-da93da20d993" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-7040-9b20-da93da20d993_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-7888-ba3f-51c849a7b964" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cd2cc-7459-7040-9b20-da93da20d993" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-7888-ba3f-51c849a7b964" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019cd2cc-7459-7311-ad0e-0ca5c76b048b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-7888-ba3f-51c849a7b964" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019cd2cc-7459-7311-ad0e-0ca5c76b048b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019cd2cc-7459-7ec2-9b59-5e94909345ad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDebtInstrumentsTable_019cd2cc-7459-7b79-a29d-106b074b34ba" xlink:to="loc_us-gaap_CreditFacilityAxis_019cd2cc-7459-7ec2-9b59-5e94909345ad" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019cd2cc-7459-7ec2-9b59-5e94909345ad_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019cd2cc-7459-7ec2-9b59-5e94909345ad" xlink:to="loc_us-gaap_CreditFacilityDomain_019cd2cc-7459-7ec2-9b59-5e94909345ad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019cd2cc-7459-766d-be45-672da8d27b5a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019cd2cc-7459-7ec2-9b59-5e94909345ad" xlink:to="loc_us-gaap_CreditFacilityDomain_019cd2cc-7459-766d-be45-672da8d27b5a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019cd2cc-7459-7b3b-ae64-ef8cd7da13f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019cd2cc-7459-766d-be45-672da8d27b5a" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019cd2cc-7459-7b3b-ae64-ef8cd7da13f8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-768d-8b66-4af6a1a5b5e3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDebtInstrumentsTable_019cd2cc-7459-7b79-a29d-106b074b34ba" xlink:to="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-768d-8b66-4af6a1a5b5e3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-768d-8b66-4af6a1a5b5e3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-768d-8b66-4af6a1a5b5e3" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-768d-8b66-4af6a1a5b5e3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7b05-a691-9615b30e5455" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-768d-8b66-4af6a1a5b5e3" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7b05-a691-9615b30e5455" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_CreditAgreementMember_019cd2cc-7459-7325-974e-1d23f1c63b80" xlink:href="trs-20260331.xsd#trs_CreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7b05-a691-9615b30e5455" xlink:to="loc_trs_CreditAgreementMember_019cd2cc-7459-7325-974e-1d23f1c63b80" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019cd2cc-7459-7c59-b58a-b04897a94311" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7b05-a691-9615b30e5455" xlink:to="loc_us-gaap_SeniorNotesMember_019cd2cc-7459-7c59-b58a-b04897a94311" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_A4.875SeniorUnsecuredNotesDue2025Member_019cd2cc-7459-76c4-ba78-0113a3ad4f3b" xlink:href="trs-20260331.xsd#trs_A4.875SeniorUnsecuredNotesDue2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7b05-a691-9615b30e5455" xlink:to="loc_trs_A4.875SeniorUnsecuredNotesDue2025Member_019cd2cc-7459-76c4-ba78-0113a3ad4f3b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_A4125SeniorUnsecuredNotesDue2029Member_019cd2cc-7459-7d7d-9dc0-c3a5d74bc51f" xlink:href="trs-20260331.xsd#trs_A4125SeniorUnsecuredNotesDue2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7b05-a691-9615b30e5455" xlink:to="loc_trs_A4125SeniorUnsecuredNotesDue2029Member_019cd2cc-7459-7d7d-9dc0-c3a5d74bc51f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndCapitalLeaseObligations_019cd2cc-7459-7668-b609-ad20fc8d2960" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-72de-9f7b-1da8be66840f" xlink:to="loc_us-gaap_DebtAndCapitalLeaseObligations_019cd2cc-7459-7668-b609-ad20fc8d2960" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue_019cd2cc-7459-728d-bdb6-e31b5cf0c575" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cd2cc-7459-72de-9f7b-1da8be66840f" xlink:to="loc_us-gaap_LongTermDebtFairValue_019cd2cc-7459-728d-bdb6-e31b5cf0c575" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDerivativeNarrativeDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#DerivativeInstrumentsDerivativeNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDerivativeNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019cd2cc-7459-7c98-ad77-00295e9aab91" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_019cd2cc-7459-7f09-9370-22a12d3d0783" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_019cd2cc-7459-7c98-ad77-00295e9aab91" xlink:to="loc_us-gaap_DerivativeTable_019cd2cc-7459-7f09-9370-22a12d3d0783" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-73c7-a053-d0b0d22e02ea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019cd2cc-7459-7f09-9370-22a12d3d0783" xlink:to="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-73c7-a053-d0b0d22e02ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-73c7-a053-d0b0d22e02ea_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-73c7-a053-d0b0d22e02ea" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-73c7-a053-d0b0d22e02ea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-7d9b-82c3-ccf78943c195" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-73c7-a053-d0b0d22e02ea" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-7d9b-82c3-ccf78943c195" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cd2cc-7459-79ec-9f45-99906f26d946" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-7d9b-82c3-ccf78943c195" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cd2cc-7459-79ec-9f45-99906f26d946" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019cd2cc-7459-7b1c-be63-e5ec7aca6d94" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-7d9b-82c3-ccf78943c195" xlink:to="loc_us-gaap_NondesignatedMember_019cd2cc-7459-7b1c-be63-e5ec7aca6d94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019cd2cc-7459-7a6b-972a-df8c9b43c172" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019cd2cc-7459-7f09-9370-22a12d3d0783" xlink:to="loc_srt_RangeAxis_019cd2cc-7459-7a6b-972a-df8c9b43c172" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cd2cc-7459-7a6b-972a-df8c9b43c172_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019cd2cc-7459-7a6b-972a-df8c9b43c172" xlink:to="loc_srt_RangeMember_019cd2cc-7459-7a6b-972a-df8c9b43c172_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cd2cc-7459-7a8b-a7ae-63ebaca37f2c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019cd2cc-7459-7a6b-972a-df8c9b43c172" xlink:to="loc_srt_RangeMember_019cd2cc-7459-7a8b-a7ae-63ebaca37f2c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019cd2cc-7459-7215-b9f8-b34c33de2eed" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cd2cc-7459-7a8b-a7ae-63ebaca37f2c" xlink:to="loc_srt_MaximumMember_019cd2cc-7459-7215-b9f8-b34c33de2eed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019cd2cc-7459-7496-a3d3-15aabcf933dc" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cd2cc-7459-7a8b-a7ae-63ebaca37f2c" xlink:to="loc_srt_MinimumMember_019cd2cc-7459-7496-a3d3-15aabcf933dc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-7d62-a6b9-40ea2ea61b12" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019cd2cc-7459-7f09-9370-22a12d3d0783" xlink:to="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-7d62-a6b9-40ea2ea61b12" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7d62-a6b9-40ea2ea61b12_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-7d62-a6b9-40ea2ea61b12" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7d62-a6b9-40ea2ea61b12_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7649-bd51-bbfc6699ea61" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019cd2cc-7459-7d62-a6b9-40ea2ea61b12" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7649-bd51-bbfc6699ea61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SeniorSecuredTermLoanMember_019cd2cc-7459-74f1-a28b-2a20fd8475d7" xlink:href="trs-20260331.xsd#trs_SeniorSecuredTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cd2cc-7459-7649-bd51-bbfc6699ea61" xlink:to="loc_trs_SeniorSecuredTermLoanMember_019cd2cc-7459-74f1-a28b-2a20fd8475d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-723b-8d6a-66ed91dbc3bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019cd2cc-7459-7f09-9370-22a12d3d0783" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-723b-8d6a-66ed91dbc3bb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-723b-8d6a-66ed91dbc3bb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-723b-8d6a-66ed91dbc3bb" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-723b-8d6a-66ed91dbc3bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-758f-890a-d58445c42c33" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-723b-8d6a-66ed91dbc3bb" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-758f-890a-d58445c42c33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019cd2cc-7459-7960-bb06-8f7f020e60d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-758f-890a-d58445c42c33" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019cd2cc-7459-7960-bb06-8f7f020e60d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_019cd2cc-7459-77d1-935c-d4bc27f1252f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-758f-890a-d58445c42c33" xlink:to="loc_us-gaap_ForeignExchangeContractMember_019cd2cc-7459-77d1-935c-d4bc27f1252f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019cd2cc-7459-7dae-b8fa-f79ea89788ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-758f-890a-d58445c42c33" xlink:to="loc_us-gaap_InterestRateSwapMember_019cd2cc-7459-7dae-b8fa-f79ea89788ab" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-7459-7f1f-97da-efa38480b27b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019cd2cc-7459-7f09-9370-22a12d3d0783" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-7459-7f1f-97da-efa38480b27b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-7f1f-97da-efa38480b27b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-7459-7f1f-97da-efa38480b27b" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-7f1f-97da-efa38480b27b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-70d3-b32e-3ff54b2c59fd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-7459-7f1f-97da-efa38480b27b" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-70d3-b32e-3ff54b2c59fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019cd2cc-7459-721d-adf4-618ff365f84d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-70d3-b32e-3ff54b2c59fd" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019cd2cc-7459-721d-adf4-618ff365f84d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_019cd2cc-7459-7100-ae0d-a4c7e087e366" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-70d3-b32e-3ff54b2c59fd" xlink:to="loc_us-gaap_CashFlowHedgingMember_019cd2cc-7459-7100-ae0d-a4c7e087e366" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DerivativeContractDateAxis_019cd2cc-7459-7d14-8c92-3b3c83f3f8fe" xlink:href="trs-20260331.xsd#trs_DerivativeContractDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019cd2cc-7459-7f09-9370-22a12d3d0783" xlink:to="loc_trs_DerivativeContractDateAxis_019cd2cc-7459-7d14-8c92-3b3c83f3f8fe" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DerivativeMaturityDateDomain_019cd2cc-7459-7d14-8c92-3b3c83f3f8fe_default" xlink:href="trs-20260331.xsd#trs_DerivativeMaturityDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_DerivativeContractDateAxis_019cd2cc-7459-7d14-8c92-3b3c83f3f8fe" xlink:to="loc_trs_DerivativeMaturityDateDomain_019cd2cc-7459-7d14-8c92-3b3c83f3f8fe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DerivativeMaturityDateDomain_019cd2cc-7459-79ce-9c56-54f07c6045a0" xlink:href="trs-20260331.xsd#trs_DerivativeMaturityDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DerivativeContractDateAxis_019cd2cc-7459-7d14-8c92-3b3c83f3f8fe" xlink:to="loc_trs_DerivativeMaturityDateDomain_019cd2cc-7459-79ce-9c56-54f07c6045a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DerivativeJune2020MaturityMember_019cd2cc-7459-70ff-a828-e255ff91b51c" xlink:href="trs-20260331.xsd#trs_DerivativeJune2020MaturityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DerivativeMaturityDateDomain_019cd2cc-7459-79ce-9c56-54f07c6045a0" xlink:to="loc_trs_DerivativeJune2020MaturityMember_019cd2cc-7459-70ff-a828-e255ff91b51c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_June2024DerivativeDomain_019cd2cc-7459-7b9a-aa5a-53dfb9e6f4c1" xlink:href="trs-20260331.xsd#trs_June2024DerivativeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DerivativeMaturityDateDomain_019cd2cc-7459-79ce-9c56-54f07c6045a0" xlink:to="loc_trs_June2024DerivativeDomain_019cd2cc-7459-7b9a-aa5a-53dfb9e6f4c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DerivativeApril2029MaturityDomain_019cd2cc-7459-792c-96c9-f0093813d5d5" xlink:href="trs-20260331.xsd#trs_DerivativeApril2029MaturityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DerivativeMaturityDateDomain_019cd2cc-7459-79ce-9c56-54f07c6045a0" xlink:to="loc_trs_DerivativeApril2029MaturityDomain_019cd2cc-7459-792c-96c9-f0093813d5d5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DerivativeApril2024MaturityDomain_019cd2cc-7459-774c-8968-2c11c5e4106b" xlink:href="trs-20260331.xsd#trs_DerivativeApril2024MaturityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DerivativeMaturityDateDomain_019cd2cc-7459-79ce-9c56-54f07c6045a0" xlink:to="loc_trs_DerivativeApril2024MaturityDomain_019cd2cc-7459-774c-8968-2c11c5e4106b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DerivativeContractDateDomain_019cd2cc-7459-721a-b67a-279756b8ce8a" xlink:href="trs-20260331.xsd#trs_DerivativeContractDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DerivativeContractDateAxis_019cd2cc-7459-7d14-8c92-3b3c83f3f8fe" xlink:to="loc_trs_DerivativeContractDateDomain_019cd2cc-7459-721a-b67a-279756b8ce8a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_February2024DerivativeContractDateDomain_019cd2cc-7459-773b-a8ec-79dd6367bb2c" xlink:href="trs-20260331.xsd#trs_February2024DerivativeContractDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DerivativeContractDateDomain_019cd2cc-7459-721a-b67a-279756b8ce8a" xlink:to="loc_trs_February2024DerivativeContractDateDomain_019cd2cc-7459-773b-a8ec-79dd6367bb2c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_019cd2cc-7459-7f34-895c-507e4886f2c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeNumberOfInstrumentsHeld"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019cd2cc-7459-7c98-ad77-00295e9aab91" xlink:to="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_019cd2cc-7459-7f34-895c-507e4886f2c8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1_019cd2cc-7459-7a85-b147-b94e3eea12a7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019cd2cc-7459-7c98-ad77-00295e9aab91" xlink:to="loc_us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1_019cd2cc-7459-7a85-b147-b94e3eea12a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFixedInterestRate_019cd2cc-7459-7250-85e6-650ad8cbfd7f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFixedInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019cd2cc-7459-7c98-ad77-00295e9aab91" xlink:to="loc_us-gaap_DerivativeFixedInterestRate_019cd2cc-7459-7250-85e6-650ad8cbfd7f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCashReceivedOnHedge_019cd2cc-7459-7eb7-82d6-ec3821843d53" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeCashReceivedOnHedge"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019cd2cc-7459-7c98-ad77-00295e9aab91" xlink:to="loc_us-gaap_DerivativeCashReceivedOnHedge_019cd2cc-7459-7eb7-82d6-ec3821843d53" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_019cd2cc-7459-7efc-9439-d6b6fa2b3df6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019cd2cc-7459-7c98-ad77-00295e9aab91" xlink:to="loc_us-gaap_DerivativeNotionalAmount_019cd2cc-7459-7efc-9439-d6b6fa2b3df6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeMaturityDates_019cd2cc-7459-7404-9f3f-8b5e35bf30dd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeMaturityDates"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019cd2cc-7459-7c98-ad77-00295e9aab91" xlink:to="loc_us-gaap_DerivativeMaturityDates_019cd2cc-7459-7404-9f3f-8b5e35bf30dd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Cashpaidatterminationofinterestrateswap_019cd2cc-7459-71a9-b365-91bb52405848" xlink:href="trs-20260331.xsd#trs_Cashpaidatterminationofinterestrateswap"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019cd2cc-7459-7c98-ad77-00295e9aab91" xlink:to="loc_trs_Cashpaidatterminationofinterestrateswap_019cd2cc-7459-71a9-b365-91bb52405848" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeNet_019cd2cc-7459-7c8b-984f-9e4ec5a4408c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFairValueOfDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019cd2cc-7459-7c98-ad77-00295e9aab91" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeNet_019cd2cc-7459-7c8b-984f-9e4ec5a4408c" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPositionDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#DerivativeInstrumentsDesignatedashedgingFinancialPositionDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPositionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_019cd2cc-7459-766f-8cd3-3bca1b023efb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019cd2cc-7459-7e7a-9479-6ab52ced7ed0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019cd2cc-7459-766f-8cd3-3bca1b023efb" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019cd2cc-7459-7e7a-9479-6ab52ced7ed0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-7459-7092-9b44-3d1a556f202f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019cd2cc-7459-7e7a-9479-6ab52ced7ed0" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-7459-7092-9b44-3d1a556f202f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-7092-9b44-3d1a556f202f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-7459-7092-9b44-3d1a556f202f" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-7092-9b44-3d1a556f202f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-7a89-a3cd-414610129d20" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-7459-7092-9b44-3d1a556f202f" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-7a89-a3cd-414610129d20" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019cd2cc-7459-75f3-98f5-b811ec166653" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-7a89-a3cd-414610129d20" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019cd2cc-7459-75f3-98f5-b811ec166653" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-7f48-8d79-be188e939275" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019cd2cc-7459-7e7a-9479-6ab52ced7ed0" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-7f48-8d79-be188e939275" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7f48-8d79-be188e939275_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-7f48-8d79-be188e939275" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7f48-8d79-be188e939275_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7b24-ae19-1b0a195ae526" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-7f48-8d79-be188e939275" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7b24-ae19-1b0a195ae526" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019cd2cc-7459-726c-8c49-bc6729de5105" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7b24-ae19-1b0a195ae526" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019cd2cc-7459-726c-8c49-bc6729de5105" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-7964-bc5c-bd83c3ae9dbc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019cd2cc-7459-7e7a-9479-6ab52ced7ed0" xlink:to="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-7964-bc5c-bd83c3ae9dbc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-7964-bc5c-bd83c3ae9dbc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-7964-bc5c-bd83c3ae9dbc" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-7964-bc5c-bd83c3ae9dbc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-7f80-a7d7-1ae65c3f35cb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-7964-bc5c-bd83c3ae9dbc" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-7f80-a7d7-1ae65c3f35cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cd2cc-7459-77f0-a055-18d23c5bd15a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-7f80-a7d7-1ae65c3f35cb" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cd2cc-7459-77f0-a055-18d23c5bd15a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_019cd2cc-7459-793b-b3ae-d24b9805b266" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019cd2cc-7459-7e7a-9479-6ab52ced7ed0" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_019cd2cc-7459-793b-b3ae-d24b9805b266" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_019cd2cc-7459-793b-b3ae-d24b9805b266_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_019cd2cc-7459-793b-b3ae-d24b9805b266" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_019cd2cc-7459-793b-b3ae-d24b9805b266_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_019cd2cc-7459-79ff-9c75-a9d4cef3ad9e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_019cd2cc-7459-793b-b3ae-d24b9805b266" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_019cd2cc-7459-79ff-9c75-a9d4cef3ad9e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsMember_019cd2cc-7459-79ff-91b2-9fbbf82e2a57" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_019cd2cc-7459-79ff-9c75-a9d4cef3ad9e" xlink:to="loc_us-gaap_OtherAssetsMember_019cd2cc-7459-79ff-91b2-9fbbf82e2a57" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesMember_019cd2cc-7459-7098-83be-4ec73faef306" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccruedLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_019cd2cc-7459-79ff-9c75-a9d4cef3ad9e" xlink:to="loc_us-gaap_AccruedLiabilitiesMember_019cd2cc-7459-7098-83be-4ec73faef306" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesMember_019cd2cc-7459-74d5-b0ba-1bc14cd9e0d8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_019cd2cc-7459-79ff-9c75-a9d4cef3ad9e" xlink:to="loc_us-gaap_OtherLiabilitiesMember_019cd2cc-7459-74d5-b0ba-1bc14cd9e0d8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral_019cd2cc-7459-7af4-81db-8ab0aa9e01ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019cd2cc-7459-766f-8cd3-3bca1b023efb" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral_019cd2cc-7459-7af4-81db-8ab0aa9e01ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_019cd2cc-7459-752f-a6a5-1ac66471c825" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019cd2cc-7459-766f-8cd3-3bca1b023efb" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_019cd2cc-7459-752f-a6a5-1ac66471c825" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPerformanceDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#DerivativeInstrumentsDesignatedashedgingFinancialPerformanceDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPerformanceDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019cd2cc-7459-7089-9402-10312284f64c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019cd2cc-7459-7ec7-b624-806b666b2909" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019cd2cc-7459-7089-9402-10312284f64c" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019cd2cc-7459-7ec7-b624-806b666b2909" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-7459-74ed-8ff3-2425820a7b86" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019cd2cc-7459-7ec7-b624-806b666b2909" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-7459-74ed-8ff3-2425820a7b86" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-74ed-8ff3-2425820a7b86_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-7459-74ed-8ff3-2425820a7b86" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-74ed-8ff3-2425820a7b86_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-7167-bfb8-4ce35f4972f3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-7459-74ed-8ff3-2425820a7b86" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-7167-bfb8-4ce35f4972f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019cd2cc-7459-7149-8ccc-015abb23763a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-7167-bfb8-4ce35f4972f3" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019cd2cc-7459-7149-8ccc-015abb23763a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-76ef-9bd8-115f1d967c78" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019cd2cc-7459-7ec7-b624-806b666b2909" xlink:to="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-76ef-9bd8-115f1d967c78" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-76ef-9bd8-115f1d967c78_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-76ef-9bd8-115f1d967c78" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-76ef-9bd8-115f1d967c78_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-7f8e-9fdd-d3f66877c9be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-76ef-9bd8-115f1d967c78" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-7f8e-9fdd-d3f66877c9be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cd2cc-7459-7405-b8bc-fb35f1f04a8b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-7f8e-9fdd-d3f66877c9be" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cd2cc-7459-7405-b8bc-fb35f1f04a8b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-7d38-adf5-e763cdb967cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019cd2cc-7459-7ec7-b624-806b666b2909" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-7d38-adf5-e763cdb967cc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7d38-adf5-e763cdb967cc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-7d38-adf5-e763cdb967cc" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7d38-adf5-e763cdb967cc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7d48-907d-b26d5a01b122" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-7d38-adf5-e763cdb967cc" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7d48-907d-b26d5a01b122" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019cd2cc-7459-7d77-aa20-344267f3c712" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7d48-907d-b26d5a01b122" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019cd2cc-7459-7d77-aa20-344267f3c712" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-786f-a3a6-3ef2536a3994" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019cd2cc-7459-7ec7-b624-806b666b2909" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-786f-a3a6-3ef2536a3994" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-786f-a3a6-3ef2536a3994_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-786f-a3a6-3ef2536a3994" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-786f-a3a6-3ef2536a3994_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7fb1-891f-82ea8650bf8c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-786f-a3a6-3ef2536a3994" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7fb1-891f-82ea8650bf8c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseMember_019cd2cc-7459-77d2-bcfe-4a39900b097d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7fb1-891f-82ea8650bf8c" xlink:to="loc_us-gaap_InterestExpenseMember_019cd2cc-7459-77d2-bcfe-4a39900b097d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DebtfinancingandrelatedexpensesMember_019cd2cc-7459-7a7d-9321-1754a3009829" xlink:href="trs-20260331.xsd#trs_DebtfinancingandrelatedexpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7fb1-891f-82ea8650bf8c" xlink:to="loc_trs_DebtfinancingandrelatedexpensesMember_019cd2cc-7459-7a7d-9321-1754a3009829" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_019cd2cc-7459-7c5c-a8ba-574df73b1a62" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7fb1-891f-82ea8650bf8c" xlink:to="loc_us-gaap_CostOfSalesMember_019cd2cc-7459-7c5c-a8ba-574df73b1a62" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019cd2cc-7459-7fb9-b447-c3edbe085186" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019cd2cc-7459-7089-9402-10312284f64c" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019cd2cc-7459-7fb9-b447-c3edbe085186" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019cd2cc-7459-7024-8159-fbdfd6ac5f25" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019cd2cc-7459-7089-9402-10312284f64c" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019cd2cc-7459-7024-8159-fbdfd6ac5f25" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPerformanceNarrativeDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#DerivativeInstrumentsDesignatedashedgingFinancialPerformanceNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPerformanceNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019cd2cc-7459-7187-b2ad-9b8beb105bec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019cd2cc-7459-7c8f-b666-37842bb1ab96" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019cd2cc-7459-7187-b2ad-9b8beb105bec" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019cd2cc-7459-7c8f-b666-37842bb1ab96" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-726b-a9b8-3f7132702812" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019cd2cc-7459-7c8f-b666-37842bb1ab96" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-726b-a9b8-3f7132702812" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-726b-a9b8-3f7132702812_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-726b-a9b8-3f7132702812" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-726b-a9b8-3f7132702812_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-73ab-ace5-4e3c7d0214e3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-726b-a9b8-3f7132702812" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-73ab-ace5-4e3c7d0214e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseMember_019cd2cc-7459-7baa-80ce-884474aecf9c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-73ab-ace5-4e3c7d0214e3" xlink:to="loc_us-gaap_InterestExpenseMember_019cd2cc-7459-7baa-80ce-884474aecf9c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-772d-85e7-31e01322bb9b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019cd2cc-7459-7c8f-b666-37842bb1ab96" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-772d-85e7-31e01322bb9b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-772d-85e7-31e01322bb9b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-772d-85e7-31e01322bb9b" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-772d-85e7-31e01322bb9b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7d29-9b8c-44588d3a996f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-772d-85e7-31e01322bb9b" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7d29-9b8c-44588d3a996f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-73b0-b0ca-25d2a816c286" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019cd2cc-7459-7c8f-b666-37842bb1ab96" xlink:to="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-73b0-b0ca-25d2a816c286" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-73b0-b0ca-25d2a816c286_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-73b0-b0ca-25d2a816c286" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-73b0-b0ca-25d2a816c286_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-7860-80f8-a341fbb160f5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-73b0-b0ca-25d2a816c286" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-7860-80f8-a341fbb160f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cd2cc-7459-727d-9b44-72b5c000bc96" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-7860-80f8-a341fbb160f5" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cd2cc-7459-727d-9b44-72b5c000bc96" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimateOfTimeToTransfer1_019cd2cc-7459-7864-8f14-c33389fec4e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimateOfTimeToTransfer1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019cd2cc-7459-7187-b2ad-9b8beb105bec" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimateOfTimeToTransfer1_019cd2cc-7459-7864-8f14-c33389fec4e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred_019cd2cc-7459-7783-b05a-35092ffd9742" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019cd2cc-7459-7187-b2ad-9b8beb105bec" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred_019cd2cc-7459-7783-b05a-35092ffd9742" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDerivativesnotdesignatedashedginginstrumentsDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#DerivativeInstrumentsDerivativesnotdesignatedashedginginstrumentsDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDerivativesnotdesignatedashedginginstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019cd2cc-7459-7565-92f6-910ba7b2f4ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_019cd2cc-7459-7588-bffa-d32a3efb14ad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_019cd2cc-7459-7565-92f6-910ba7b2f4ae" xlink:to="loc_us-gaap_DerivativeTable_019cd2cc-7459-7588-bffa-d32a3efb14ad" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-7acd-b11c-050fac23e0bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019cd2cc-7459-7588-bffa-d32a3efb14ad" xlink:to="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-7acd-b11c-050fac23e0bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-7acd-b11c-050fac23e0bb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-7acd-b11c-050fac23e0bb" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-7acd-b11c-050fac23e0bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-79a3-ab85-88e1113d2b9f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cd2cc-7459-7acd-b11c-050fac23e0bb" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-79a3-ab85-88e1113d2b9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019cd2cc-7459-78c0-a160-b5c5477a59eb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019cd2cc-7459-79a3-ab85-88e1113d2b9f" xlink:to="loc_us-gaap_NondesignatedMember_019cd2cc-7459-78c0-a160-b5c5477a59eb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-78d1-9d92-a4cc0361f82f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019cd2cc-7459-7588-bffa-d32a3efb14ad" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-78d1-9d92-a4cc0361f82f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-78d1-9d92-a4cc0361f82f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-78d1-9d92-a4cc0361f82f" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-78d1-9d92-a4cc0361f82f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-723a-98b5-22725a6b2dd1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-78d1-9d92-a4cc0361f82f" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-723a-98b5-22725a6b2dd1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_019cd2cc-7459-7cfd-8bd5-74eff1ed7fdd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-723a-98b5-22725a6b2dd1" xlink:to="loc_us-gaap_ForeignExchangeContractMember_019cd2cc-7459-7cfd-8bd5-74eff1ed7fdd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrencySwapMember_019cd2cc-7459-7d05-829a-6eac043930b7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CurrencySwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-723a-98b5-22725a6b2dd1" xlink:to="loc_us-gaap_CurrencySwapMember_019cd2cc-7459-7d05-829a-6eac043930b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_019cd2cc-7459-76c1-be69-26a17f341607" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019cd2cc-7459-7565-92f6-910ba7b2f4ae" xlink:to="loc_us-gaap_DerivativeNotionalAmount_019cd2cc-7459-76c1-be69-26a17f341607" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnForeignCurrencyDerivativesRecordedInEarningsNet_019cd2cc-7459-7de8-b4cf-274890ad0aff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnForeignCurrencyDerivativesRecordedInEarningsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019cd2cc-7459-7565-92f6-910ba7b2f4ae" xlink:to="loc_us-gaap_GainLossOnForeignCurrencyDerivativesRecordedInEarningsNet_019cd2cc-7459-7de8-b4cf-274890ad0aff" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsFairValueMeasurementsDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#DerivativeInstrumentsFairValueMeasurementsDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsFairValueMeasurementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019cd2cc-7459-702e-909f-cfb717789779" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019cd2cc-7459-74d6-bca9-b5ece6d66b70" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019cd2cc-7459-702e-909f-cfb717789779" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019cd2cc-7459-74d6-bca9-b5ece6d66b70" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019cd2cc-7459-765d-84f3-04c79c73df0e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019cd2cc-7459-74d6-bca9-b5ece6d66b70" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019cd2cc-7459-765d-84f3-04c79c73df0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019cd2cc-7459-765d-84f3-04c79c73df0e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019cd2cc-7459-765d-84f3-04c79c73df0e" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019cd2cc-7459-765d-84f3-04c79c73df0e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019cd2cc-7459-7c9a-be66-2a2684ead6e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019cd2cc-7459-765d-84f3-04c79c73df0e" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019cd2cc-7459-7c9a-be66-2a2684ead6e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019cd2cc-7459-7411-a7a7-51a8f60b687f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019cd2cc-7459-7c9a-be66-2a2684ead6e8" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019cd2cc-7459-7411-a7a7-51a8f60b687f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-7022-a1a7-dea989e8f824" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019cd2cc-7459-74d6-bca9-b5ece6d66b70" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-7022-a1a7-dea989e8f824" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7022-a1a7-dea989e8f824_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-7022-a1a7-dea989e8f824" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7022-a1a7-dea989e8f824_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7304-8928-f799ea221169" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-7459-7022-a1a7-dea989e8f824" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7304-8928-f799ea221169" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019cd2cc-7459-711f-9791-5091d2702f90" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7304-8928-f799ea221169" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019cd2cc-7459-711f-9791-5091d2702f90" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_019cd2cc-7459-7d80-a389-28e1e31b31dc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-7459-7304-8928-f799ea221169" xlink:to="loc_us-gaap_ForeignExchangeContractMember_019cd2cc-7459-7d80-a389-28e1e31b31dc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-7459-7907-8e08-da6fad93c27f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019cd2cc-7459-74d6-bca9-b5ece6d66b70" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-7459-7907-8e08-da6fad93c27f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-7907-8e08-da6fad93c27f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-7459-7907-8e08-da6fad93c27f" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-7907-8e08-da6fad93c27f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-7e71-a2f3-c71352079f69" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-7459-7907-8e08-da6fad93c27f" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-7e71-a2f3-c71352079f69" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019cd2cc-7459-7979-8e41-56c1b865b1fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-7459-7e71-a2f3-c71352079f69" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019cd2cc-7459-7979-8e41-56c1b865b1fb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019cd2cc-7459-705c-8f4d-53111de7574a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019cd2cc-7459-74d6-bca9-b5ece6d66b70" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019cd2cc-7459-705c-8f4d-53111de7574a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019cd2cc-7459-705c-8f4d-53111de7574a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019cd2cc-7459-705c-8f4d-53111de7574a" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019cd2cc-7459-705c-8f4d-53111de7574a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019cd2cc-7459-710c-9b4d-258aeb34313e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019cd2cc-7459-705c-8f4d-53111de7574a" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019cd2cc-7459-710c-9b4d-258aeb34313e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019cd2cc-7459-7da6-8d7a-024e931ecefd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019cd2cc-7459-710c-9b4d-258aeb34313e" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019cd2cc-7459-7da6-8d7a-024e931ecefd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cd2cc-7459-793f-8ff9-756e95030981" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019cd2cc-7459-74d6-bca9-b5ece6d66b70" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cd2cc-7459-793f-8ff9-756e95030981" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-793f-8ff9-756e95030981_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cd2cc-7459-793f-8ff9-756e95030981" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-793f-8ff9-756e95030981_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-7428-8f45-9f5f2a5400ef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cd2cc-7459-793f-8ff9-756e95030981" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-7428-8f45-9f5f2a5400ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019cd2cc-7459-7117-91f1-2ba5ee15ce7f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-7428-8f45-9f5f2a5400ef" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019cd2cc-7459-7117-91f1-2ba5ee15ce7f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019cd2cc-7459-77d7-ab5e-a595c1607666" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-7428-8f45-9f5f2a5400ef" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019cd2cc-7459-77d7-ab5e-a595c1607666" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019cd2cc-7459-78ab-a68d-9f267a6081e4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cd2cc-7459-7428-8f45-9f5f2a5400ef" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019cd2cc-7459-78ab-a68d-9f267a6081e4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsInHedgesAtFairValueNet_019cd2cc-7459-7c5b-9347-1322f474709c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsInHedgesAtFairValueNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019cd2cc-7459-702e-909f-cfb717789779" xlink:to="loc_us-gaap_DerivativeInstrumentsInHedgesAtFairValueNet_019cd2cc-7459-7c5b-9347-1322f474709c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherDerivativesNotDesignatedAsHedgingInstrumentsAtFairValueNet_019cd2cc-7459-751e-9cba-c1f7870e6a43" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherDerivativesNotDesignatedAsHedgingInstrumentsAtFairValueNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019cd2cc-7459-702e-909f-cfb717789779" xlink:to="loc_us-gaap_OtherDerivativesNotDesignatedAsHedgingInstrumentsAtFairValueNet_019cd2cc-7459-751e-9cba-c1f7870e6a43" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsandContingenciesAsbestosNarrativeDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#CommitmentsandContingenciesAsbestosNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsandContingenciesAsbestosNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-79e3-a7ac-993b2935b333" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7b6d-8069-f9899f71ba3a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-79e3-a7ac-993b2935b333" xlink:to="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7b6d-8069-f9899f71ba3a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-7f92-ae9f-aab2955da97d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7b6d-8069-f9899f71ba3a" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-7f92-ae9f-aab2955da97d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7f92-ae9f-aab2955da97d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-7f92-ae9f-aab2955da97d" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7f92-ae9f-aab2955da97d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7e82-b17f-7ae315fade16" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-7f92-ae9f-aab2955da97d" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7e82-b17f-7ae315fade16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_019cd2cc-7459-7550-8185-cfbd8c28bd4b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7e82-b17f-7ae315fade16" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_019cd2cc-7459-7550-8185-cfbd8c28bd4b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_019cd2cc-7459-7878-9134-05bca4694042" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7b6d-8069-f9899f71ba3a" xlink:to="loc_srt_LitigationCaseAxis_019cd2cc-7459-7878-9134-05bca4694042" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019cd2cc-7459-7878-9134-05bca4694042_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_019cd2cc-7459-7878-9134-05bca4694042" xlink:to="loc_srt_LitigationCaseTypeDomain_019cd2cc-7459-7878-9134-05bca4694042_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019cd2cc-7459-7d07-9c84-066799020aed" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_019cd2cc-7459-7878-9134-05bca4694042" xlink:to="loc_srt_LitigationCaseTypeDomain_019cd2cc-7459-7d07-9c84-066799020aed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtTypeAxis_019cd2cc-7459-7e15-9ac7-5e50d548418c" xlink:href="trs-20260331.xsd#trs_DamagesSoughtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7b6d-8069-f9899f71ba3a" xlink:to="loc_trs_DamagesSoughtTypeAxis_019cd2cc-7459-7e15-9ac7-5e50d548418c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtTypeDomain_019cd2cc-7459-7e15-9ac7-5e50d548418c_default" xlink:href="trs-20260331.xsd#trs_DamagesSoughtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_DamagesSoughtTypeAxis_019cd2cc-7459-7e15-9ac7-5e50d548418c" xlink:to="loc_trs_DamagesSoughtTypeDomain_019cd2cc-7459-7e15-9ac7-5e50d548418c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtTypeDomain_019cd2cc-7459-7186-bf3e-9dd78bb993fb" xlink:href="trs-20260331.xsd#trs_DamagesSoughtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DamagesSoughtTypeAxis_019cd2cc-7459-7e15-9ac7-5e50d548418c" xlink:to="loc_trs_DamagesSoughtTypeDomain_019cd2cc-7459-7186-bf3e-9dd78bb993fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_PunitiveOnlyDamagesMember_019cd2cc-7459-7376-8370-4c93370f7f1a" xlink:href="trs-20260331.xsd#trs_PunitiveOnlyDamagesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtTypeDomain_019cd2cc-7459-7186-bf3e-9dd78bb993fb" xlink:to="loc_trs_PunitiveOnlyDamagesMember_019cd2cc-7459-7376-8370-4c93370f7f1a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_CompensatoryOnlyDamagesMember_019cd2cc-7459-7c69-8fbc-be05d4202628" xlink:href="trs-20260331.xsd#trs_CompensatoryOnlyDamagesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtTypeDomain_019cd2cc-7459-7186-bf3e-9dd78bb993fb" xlink:to="loc_trs_CompensatoryOnlyDamagesMember_019cd2cc-7459-7c69-8fbc-be05d4202628" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-76cf-98a5-0b3e950555ea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7b6d-8069-f9899f71ba3a" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-76cf-98a5-0b3e950555ea" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-76cf-98a5-0b3e950555ea_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-76cf-98a5-0b3e950555ea" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-76cf-98a5-0b3e950555ea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7a18-b52c-adaea40100b5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-76cf-98a5-0b3e950555ea" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7a18-b52c-adaea40100b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AsbestosIssueMember_019cd2cc-7459-700b-bd74-92787b646fb9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AsbestosIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7a18-b52c-adaea40100b5" xlink:to="loc_us-gaap_AsbestosIssueMember_019cd2cc-7459-700b-bd74-92787b646fb9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalIssueMember_019cd2cc-7459-7660-b0b5-aec18b55c8c5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EnvironmentalIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7a18-b52c-adaea40100b5" xlink:to="loc_us-gaap_EnvironmentalIssueMember_019cd2cc-7459-7660-b0b5-aec18b55c8c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_019cd2cc-7459-7fbd-84e3-b1d82b7a05a1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7b6d-8069-f9899f71ba3a" xlink:to="loc_us-gaap_LitigationStatusAxis_019cd2cc-7459-7fbd-84e3-b1d82b7a05a1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-7fbd-84e3-b1d82b7a05a1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_019cd2cc-7459-7fbd-84e3-b1d82b7a05a1" xlink:to="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-7fbd-84e3-b1d82b7a05a1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-7865-b214-03a27a52abdb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_019cd2cc-7459-7fbd-84e3-b1d82b7a05a1" xlink:to="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-7865-b214-03a27a52abdb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_019cd2cc-7459-7f5b-88d3-977594496be3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PendingLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-7865-b214-03a27a52abdb" xlink:to="loc_us-gaap_PendingLitigationMember_019cd2cc-7459-7f5b-88d3-977594496be3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019cd2cc-7459-7b99-ae3a-0e9eb363ae06" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7b6d-8069-f9899f71ba3a" xlink:to="loc_srt_RangeAxis_019cd2cc-7459-7b99-ae3a-0e9eb363ae06" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cd2cc-7459-7b99-ae3a-0e9eb363ae06_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019cd2cc-7459-7b99-ae3a-0e9eb363ae06" xlink:to="loc_srt_RangeMember_019cd2cc-7459-7b99-ae3a-0e9eb363ae06_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cd2cc-7459-705b-a5b1-4d95b2a0338b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019cd2cc-7459-7b99-ae3a-0e9eb363ae06" xlink:to="loc_srt_RangeMember_019cd2cc-7459-705b-a5b1-4d95b2a0338b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019cd2cc-7459-78b2-9be6-4616eb974404" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cd2cc-7459-705b-a5b1-4d95b2a0338b" xlink:to="loc_srt_MinimumMember_019cd2cc-7459-78b2-9be6-4616eb974404" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019cd2cc-7459-707a-86cf-3a24a60aa764" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cd2cc-7459-705b-a5b1-4d95b2a0338b" xlink:to="loc_srt_MaximumMember_019cd2cc-7459-707a-86cf-3a24a60aa764" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesSubjectToCompromiseAsbestosObligations_019cd2cc-7459-762c-b650-ddfa63e6e499" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesSubjectToCompromiseAsbestosObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-79e3-a7ac-993b2935b333" xlink:to="loc_us-gaap_LiabilitiesSubjectToCompromiseAsbestosObligations_019cd2cc-7459-762c-b650-ddfa63e6e499" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyDamagesSoughtValue_019cd2cc-7459-73c1-99cf-8ed9cf6841b2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyDamagesSoughtValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-79e3-a7ac-993b2935b333" xlink:to="loc_us-gaap_LossContingencyDamagesSoughtValue_019cd2cc-7459-73c1-99cf-8ed9cf6841b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LossContingencyPendingCasesNumber_019cd2cc-7459-7ae2-922f-57bd997b0869" xlink:href="trs-20260331.xsd#trs_LossContingencyPendingCasesNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-79e3-a7ac-993b2935b333" xlink:to="loc_trs_LossContingencyPendingCasesNumber_019cd2cc-7459-7ae2-922f-57bd997b0869" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyPendingClaimsNumber_019cd2cc-7459-74f7-a680-f81e804677cf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyPendingClaimsNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-79e3-a7ac-993b2935b333" xlink:to="loc_us-gaap_LossContingencyPendingClaimsNumber_019cd2cc-7459-74f7-a680-f81e804677cf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought_019cd2cc-7459-7beb-b64c-958e31cc2743" xlink:href="trs-20260331.xsd#trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-79e3-a7ac-993b2935b333" xlink:to="loc_trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought_019cd2cc-7459-7beb-b64c-958e31cc2743" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementExpense_019cd2cc-7459-7d27-86e1-61f9ba640647" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationSettlementExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-79e3-a7ac-993b2935b333" xlink:to="loc_us-gaap_LitigationSettlementExpense_019cd2cc-7459-7d27-86e1-61f9ba640647" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNewClaimsFiledNumber_019cd2cc-7459-73c5-9f94-97a2f71b03d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNewClaimsFiledNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-79e3-a7ac-993b2935b333" xlink:to="loc_us-gaap_LossContingencyNewClaimsFiledNumber_019cd2cc-7459-73c5-9f94-97a2f71b03d4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_PercentageOfSettlementAndDefenseCostsCoveredByInsurance_019cd2cc-7459-7c51-8c51-66fcc34d4c10" xlink:href="trs-20260331.xsd#trs_PercentageOfSettlementAndDefenseCostsCoveredByInsurance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-79e3-a7ac-993b2935b333" xlink:to="loc_trs_PercentageOfSettlementAndDefenseCostsCoveredByInsurance_019cd2cc-7459-7c51-8c51-66fcc34d4c10" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LegalFees_019cd2cc-7459-7db6-b33e-742672b5890f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LegalFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-79e3-a7ac-993b2935b333" xlink:to="loc_us-gaap_LegalFees_019cd2cc-7459-7db6-b33e-742672b5890f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Impactofchangeinaccountingprinciple_019cd2cc-7459-71a5-a505-49584c7577d3" xlink:href="trs-20260331.xsd#trs_Impactofchangeinaccountingprinciple"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-79e3-a7ac-993b2935b333" xlink:to="loc_trs_Impactofchangeinaccountingprinciple_019cd2cc-7459-71a5-a505-49584c7577d3" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019cd2cc-7459-7288-b4dc-b46da4b22ef3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-79e3-a7ac-993b2935b333" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019cd2cc-7459-7288-b4dc-b46da4b22ef3" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyRelatedReceivableCarryingValuePeriodIncreaseDecrease_019dcf30-04df-7285-ba98-51bbcb3834b1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyRelatedReceivableCarryingValuePeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-79e3-a7ac-993b2935b333" xlink:to="loc_us-gaap_LossContingencyRelatedReceivableCarryingValuePeriodIncreaseDecrease_019dcf30-04df-7285-ba98-51bbcb3834b1" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsandContingenciesAsbestosClaimantandSettlementDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#CommitmentsandContingenciesAsbestosClaimantandSettlementDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsandContingenciesAsbestosClaimantandSettlementDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7d46-89a3-72e6f42d8595" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-790e-a72a-93b733061a7d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7d46-89a3-72e6f42d8595" xlink:to="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-790e-a72a-93b733061a7d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_019cd2cc-7459-7199-a2a0-a7b05fcddfdb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-790e-a72a-93b733061a7d" xlink:to="loc_us-gaap_LitigationStatusAxis_019cd2cc-7459-7199-a2a0-a7b05fcddfdb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-7199-a2a0-a7b05fcddfdb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_019cd2cc-7459-7199-a2a0-a7b05fcddfdb" xlink:to="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-7199-a2a0-a7b05fcddfdb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-71ea-bc6d-3a71c875dc50" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_019cd2cc-7459-7199-a2a0-a7b05fcddfdb" xlink:to="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-71ea-bc6d-3a71c875dc50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_019cd2cc-7459-7b5d-aabe-e2c5b7baea43" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PendingLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-71ea-bc6d-3a71c875dc50" xlink:to="loc_us-gaap_PendingLitigationMember_019cd2cc-7459-7b5d-aabe-e2c5b7baea43" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-73f3-b9b1-7e653971e71b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-790e-a72a-93b733061a7d" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-73f3-b9b1-7e653971e71b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-73f3-b9b1-7e653971e71b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-73f3-b9b1-7e653971e71b" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-73f3-b9b1-7e653971e71b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7bb5-8006-a3eb1211d5d2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-73f3-b9b1-7e653971e71b" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7bb5-8006-a3eb1211d5d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AsbestosIssueMember_019cd2cc-7459-7f52-ab6e-3b4f713b0e45" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AsbestosIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7bb5-8006-a3eb1211d5d2" xlink:to="loc_us-gaap_AsbestosIssueMember_019cd2cc-7459-7f52-ab6e-3b4f713b0e45" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyPendingClaimsNumber_019cd2cc-7459-7aa5-a178-c28a551ff28c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyPendingClaimsNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7d46-89a3-72e6f42d8595" xlink:to="loc_us-gaap_LossContingencyPendingClaimsNumber_019cd2cc-7459-7aa5-a178-c28a551ff28c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNewClaimsFiledNumber_019cd2cc-7459-70f3-a16e-90be9ce8b871" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNewClaimsFiledNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7d46-89a3-72e6f42d8595" xlink:to="loc_us-gaap_LossContingencyNewClaimsFiledNumber_019cd2cc-7459-70f3-a16e-90be9ce8b871" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyClaimsDismissedNumber_019cd2cc-7459-7290-b416-e38e4375163f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyClaimsDismissedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7d46-89a3-72e6f42d8595" xlink:to="loc_us-gaap_LossContingencyClaimsDismissedNumber_019cd2cc-7459-7290-b416-e38e4375163f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyClaimsSettledNumber_019cd2cc-7459-71a9-ad8a-4c87f9ecb22a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyClaimsSettledNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7d46-89a3-72e6f42d8595" xlink:to="loc_us-gaap_LossContingencyClaimsSettledNumber_019cd2cc-7459-71a9-ad8a-4c87f9ecb22a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LossContingencySettlementAgreementAverageConsideration_019cd2cc-7459-733e-a753-12b9e4eed197" xlink:href="trs-20260331.xsd#trs_LossContingencySettlementAgreementAverageConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7d46-89a3-72e6f42d8595" xlink:to="loc_trs_LossContingencySettlementAgreementAverageConsideration_019cd2cc-7459-733e-a753-12b9e4eed197" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LegalFees_019cd2cc-7459-715b-8f10-097f19ddb211" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LegalFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7d46-89a3-72e6f42d8595" xlink:to="loc_us-gaap_LegalFees_019cd2cc-7459-715b-8f10-097f19ddb211" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsandContingenciesAsbestosDamagesSoughtDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#CommitmentsandContingenciesAsbestosDamagesSoughtDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsandContingenciesAsbestosDamagesSoughtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-735a-b537-da31f4aff7ea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7566-bba3-5754613575fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-735a-b537-da31f4aff7ea" xlink:to="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7566-bba3-5754613575fb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-77de-96ef-b7bb53dc23b5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7566-bba3-5754613575fb" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-77de-96ef-b7bb53dc23b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-77de-96ef-b7bb53dc23b5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-77de-96ef-b7bb53dc23b5" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-77de-96ef-b7bb53dc23b5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7369-9af1-df391e30ef6e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-77de-96ef-b7bb53dc23b5" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7369-9af1-df391e30ef6e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AsbestosIssueMember_019cd2cc-7459-7365-b594-01a7929951cb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AsbestosIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7369-9af1-df391e30ef6e" xlink:to="loc_us-gaap_AsbestosIssueMember_019cd2cc-7459-7365-b594-01a7929951cb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_019cd2cc-7459-7e71-b9b5-ad935fa1ea65" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7566-bba3-5754613575fb" xlink:to="loc_us-gaap_LitigationStatusAxis_019cd2cc-7459-7e71-b9b5-ad935fa1ea65" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-7e71-b9b5-ad935fa1ea65_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_019cd2cc-7459-7e71-b9b5-ad935fa1ea65" xlink:to="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-7e71-b9b5-ad935fa1ea65_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-7255-8c43-c4db67c1d33e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_019cd2cc-7459-7e71-b9b5-ad935fa1ea65" xlink:to="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-7255-8c43-c4db67c1d33e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_019cd2cc-7459-7909-8a3d-17c0edaf3edb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PendingLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-7255-8c43-c4db67c1d33e" xlink:to="loc_us-gaap_PendingLitigationMember_019cd2cc-7459-7909-8a3d-17c0edaf3edb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtTypeAxis_019cd2cc-7459-791d-a6ad-c5e618eb34e9" xlink:href="trs-20260331.xsd#trs_DamagesSoughtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7566-bba3-5754613575fb" xlink:to="loc_trs_DamagesSoughtTypeAxis_019cd2cc-7459-791d-a6ad-c5e618eb34e9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtTypeDomain_019cd2cc-7459-791d-a6ad-c5e618eb34e9_default" xlink:href="trs-20260331.xsd#trs_DamagesSoughtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_DamagesSoughtTypeAxis_019cd2cc-7459-791d-a6ad-c5e618eb34e9" xlink:to="loc_trs_DamagesSoughtTypeDomain_019cd2cc-7459-791d-a6ad-c5e618eb34e9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtTypeDomain_019cd2cc-7459-71be-83f2-ec567527d416" xlink:href="trs-20260331.xsd#trs_DamagesSoughtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DamagesSoughtTypeAxis_019cd2cc-7459-791d-a6ad-c5e618eb34e9" xlink:to="loc_trs_DamagesSoughtTypeDomain_019cd2cc-7459-71be-83f2-ec567527d416" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_CompensatoryOnlyDamagesMember_019cd2cc-7459-7209-9478-afd68e4d0bae" xlink:href="trs-20260331.xsd#trs_CompensatoryOnlyDamagesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtTypeDomain_019cd2cc-7459-71be-83f2-ec567527d416" xlink:to="loc_trs_CompensatoryOnlyDamagesMember_019cd2cc-7459-7209-9478-afd68e4d0bae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_PunitiveOnlyDamagesMember_019cd2cc-7459-7416-b780-6c14472f4a6d" xlink:href="trs-20260331.xsd#trs_PunitiveOnlyDamagesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtTypeDomain_019cd2cc-7459-71be-83f2-ec567527d416" xlink:to="loc_trs_PunitiveOnlyDamagesMember_019cd2cc-7459-7416-b780-6c14472f4a6d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtRangeAxis_019cd2cc-7459-7198-8e5c-9aba389bea0c" xlink:href="trs-20260331.xsd#trs_DamagesSoughtRangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7566-bba3-5754613575fb" xlink:to="loc_trs_DamagesSoughtRangeAxis_019cd2cc-7459-7198-8e5c-9aba389bea0c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtDomain_019cd2cc-7459-7198-8e5c-9aba389bea0c_default" xlink:href="trs-20260331.xsd#trs_DamagesSoughtDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_DamagesSoughtRangeAxis_019cd2cc-7459-7198-8e5c-9aba389bea0c" xlink:to="loc_trs_DamagesSoughtDomain_019cd2cc-7459-7198-8e5c-9aba389bea0c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtDomain_019cd2cc-7459-71cd-b7cc-afa307f1b0de" xlink:href="trs-20260331.xsd#trs_DamagesSoughtDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DamagesSoughtRangeAxis_019cd2cc-7459-7198-8e5c-9aba389bea0c" xlink:to="loc_trs_DamagesSoughtDomain_019cd2cc-7459-71cd-b7cc-afa307f1b0de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Range1Member_019cd2cc-7459-79f1-badf-d539fc22a805" xlink:href="trs-20260331.xsd#trs_Range1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtDomain_019cd2cc-7459-71cd-b7cc-afa307f1b0de" xlink:to="loc_trs_Range1Member_019cd2cc-7459-79f1-badf-d539fc22a805" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Range2Member_019cd2cc-7459-7593-a61a-b9b82ae3b81c" xlink:href="trs-20260331.xsd#trs_Range2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtDomain_019cd2cc-7459-71cd-b7cc-afa307f1b0de" xlink:to="loc_trs_Range2Member_019cd2cc-7459-7593-a61a-b9b82ae3b81c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Range3Member_019cd2cc-7459-7d49-8611-61831f767b6c" xlink:href="trs-20260331.xsd#trs_Range3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtDomain_019cd2cc-7459-71cd-b7cc-afa307f1b0de" xlink:to="loc_trs_Range3Member_019cd2cc-7459-7d49-8611-61831f767b6c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtRangeDomain_019cd2cc-7459-7b21-aae4-82a5d166d752" xlink:href="trs-20260331.xsd#trs_DamagesSoughtRangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DamagesSoughtRangeAxis_019cd2cc-7459-7198-8e5c-9aba389bea0c" xlink:to="loc_trs_DamagesSoughtRangeDomain_019cd2cc-7459-7b21-aae4-82a5d166d752" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019cd2cc-7459-70f1-adff-8c12ddb4070b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7566-bba3-5754613575fb" xlink:to="loc_srt_RangeAxis_019cd2cc-7459-70f1-adff-8c12ddb4070b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cd2cc-7459-70f1-adff-8c12ddb4070b_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019cd2cc-7459-70f1-adff-8c12ddb4070b" xlink:to="loc_srt_RangeMember_019cd2cc-7459-70f1-adff-8c12ddb4070b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cd2cc-7459-745c-8604-25a3abf8e23c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019cd2cc-7459-70f1-adff-8c12ddb4070b" xlink:to="loc_srt_RangeMember_019cd2cc-7459-745c-8604-25a3abf8e23c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019cd2cc-7459-76f2-ba75-27dfaea323c7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cd2cc-7459-745c-8604-25a3abf8e23c" xlink:to="loc_srt_MinimumMember_019cd2cc-7459-76f2-ba75-27dfaea323c7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019cd2cc-7459-7806-9209-1f52cc0b8ce8" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cd2cc-7459-745c-8604-25a3abf8e23c" xlink:to="loc_srt_MaximumMember_019cd2cc-7459-7806-9209-1f52cc0b8ce8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyDamagesSoughtValue_019cd2cc-7459-708f-b9d3-17e93d68ef1a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyDamagesSoughtValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-735a-b537-da31f4aff7ea" xlink:to="loc_us-gaap_LossContingencyDamagesSoughtValue_019cd2cc-7459-708f-b9d3-17e93d68ef1a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought_019cd2cc-7459-7724-9791-f26bbef836f0" xlink:href="trs-20260331.xsd#trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-735a-b537-da31f4aff7ea" xlink:to="loc_trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought_019cd2cc-7459-7724-9791-f26bbef836f0" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentandContingenciesAsbestosLiabilityandInsuranceRecoveryAssetDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#CommitmentandContingenciesAsbestosLiabilityandInsuranceRecoveryAssetDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentandContingenciesAsbestosLiabilityandInsuranceRecoveryAssetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7333-9fbd-8debad7cbc78" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7d87-ae01-bc85af889aa7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7333-9fbd-8debad7cbc78" xlink:to="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7d87-ae01-bc85af889aa7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7886-b5f2-b3f200efbae6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7d87-ae01-bc85af889aa7" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7886-b5f2-b3f200efbae6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7886-b5f2-b3f200efbae6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7886-b5f2-b3f200efbae6" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7886-b5f2-b3f200efbae6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-74f0-a04f-01a1a8b7e780" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7886-b5f2-b3f200efbae6" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-74f0-a04f-01a1a8b7e780" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AsbestosIssueMember_019cd2cc-7459-7de9-9de6-4f3b5795d5a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AsbestosIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-74f0-a04f-01a1a8b7e780" xlink:to="loc_us-gaap_AsbestosIssueMember_019cd2cc-7459-7de9-9de6-4f3b5795d5a4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGross_019cd2cc-7459-79d1-9349-3e26b8a9c8d6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7333-9fbd-8debad7cbc78" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGross_019cd2cc-7459-79d1-9349-3e26b8a9c8d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019cd2cc-7459-7ea9-86e1-07c02a6cb6bc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7333-9fbd-8debad7cbc78" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019cd2cc-7459-7ea9-86e1-07c02a6cb6bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPaymentForClaims_019cd2cc-7459-7f43-aad7-ab861e56d610" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPaymentForClaims"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7333-9fbd-8debad7cbc78" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPaymentForClaims_019cd2cc-7459-7f43-aad7-ab861e56d610" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualCarryingValueCurrent_019cd2cc-7459-7ed6-bdf1-2ab636a1481b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyAccrualCarryingValueCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7333-9fbd-8debad7cbc78" xlink:to="loc_us-gaap_LossContingencyAccrualCarryingValueCurrent_019cd2cc-7459-7ed6-bdf1-2ab636a1481b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualCarryingValueNoncurrent_019cd2cc-7459-793a-a3f1-f9b10a19797e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyAccrualCarryingValueNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7333-9fbd-8debad7cbc78" xlink:to="loc_us-gaap_LossContingencyAccrualCarryingValueNoncurrent_019cd2cc-7459-793a-a3f1-f9b10a19797e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyReceivable_019cd2cc-7459-7652-905c-fe6e5a1b7bf5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7333-9fbd-8debad7cbc78" xlink:to="loc_us-gaap_LossContingencyReceivable_019cd2cc-7459-7652-905c-fe6e5a1b7bf5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyRelatedReceivableCarryingValuePeriodIncreaseDecrease_019cd2cc-7459-7da8-96d5-e6a0cee44b66" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyRelatedReceivableCarryingValuePeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7333-9fbd-8debad7cbc78" xlink:to="loc_us-gaap_LossContingencyRelatedReceivableCarryingValuePeriodIncreaseDecrease_019cd2cc-7459-7da8-96d5-e6a0cee44b66" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyReceivableProceeds_019cd2cc-7459-7115-8680-4957f75722d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyReceivableProceeds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7333-9fbd-8debad7cbc78" xlink:to="loc_us-gaap_LossContingencyReceivableProceeds_019cd2cc-7459-7115-8680-4957f75722d4" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNet_019cd2cc-7459-789f-9bf4-26105640fe30" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7333-9fbd-8debad7cbc78" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNet_019cd2cc-7459-789f-9bf4-26105640fe30" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPeriodIncreaseDecrease_019cd2cc-7459-7ecc-8c31-3aff83023599" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7333-9fbd-8debad7cbc78" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPeriodIncreaseDecrease_019cd2cc-7459-7ecc-8c31-3aff83023599" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPaymentForClaims_019cd2cc-7459-74b8-9ab2-6209a7f9a1a6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPaymentForClaims"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7333-9fbd-8debad7cbc78" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPaymentForClaims_019cd2cc-7459-74b8-9ab2-6209a7f9a1a6" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyReceivableCurrent_019cd2cc-7459-72a1-acbf-334300c0a063" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyReceivableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7333-9fbd-8debad7cbc78" xlink:to="loc_us-gaap_LossContingencyReceivableCurrent_019cd2cc-7459-72a1-acbf-334300c0a063" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyReceivableNoncurrent_019cd2cc-7459-7075-bae8-ba52ce84ea43" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyReceivableNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7333-9fbd-8debad7cbc78" xlink:to="loc_us-gaap_LossContingencyReceivableNoncurrent_019cd2cc-7459-7075-bae8-ba52ce84ea43" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentandContingenciesAsbestosRelatedCostsBenefitDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#CommitmentandContingenciesAsbestosRelatedCostsBenefitDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentandContingenciesAsbestosRelatedCostsBenefitDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7831-b35e-5feb49362b4f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7bc6-a2e3-745c66082127" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7831-b35e-5feb49362b4f" xlink:to="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7bc6-a2e3-745c66082127" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7d76-82f5-5a202076a26e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7bc6-a2e3-745c66082127" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7d76-82f5-5a202076a26e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7d76-82f5-5a202076a26e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7d76-82f5-5a202076a26e" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7d76-82f5-5a202076a26e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7f8a-a5d4-ee8623167cf3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7d76-82f5-5a202076a26e" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7f8a-a5d4-ee8623167cf3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AsbestosIssueMember_019cd2cc-7459-7296-93a8-158cee0782de" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AsbestosIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7f8a-a5d4-ee8623167cf3" xlink:to="loc_us-gaap_AsbestosIssueMember_019cd2cc-7459-7296-93a8-158cee0782de" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019cd2cc-7459-73c5-82df-103353e7cd9a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7831-b35e-5feb49362b4f" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019cd2cc-7459-73c5-82df-103353e7cd9a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPeriodIncreaseDecrease_019cd2cc-7459-7c57-a98b-eb47c2c7c92c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7831-b35e-5feb49362b4f" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPeriodIncreaseDecrease_019cd2cc-7459-7c57-a98b-eb47c2c7c92c" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsandContingenciesOrdinaryCourseClaimsDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#CommitmentsandContingenciesOrdinaryCourseClaimsDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsandContingenciesOrdinaryCourseClaimsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-74c4-af26-b0e030d219e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-724f-80ca-dee7b4158827" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-74c4-af26-b0e030d219e0" xlink:to="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-724f-80ca-dee7b4158827" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_019cd2cc-7459-714b-be47-e2f7934c64e4" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-724f-80ca-dee7b4158827" xlink:to="loc_srt_LitigationCaseAxis_019cd2cc-7459-714b-be47-e2f7934c64e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019cd2cc-7459-714b-be47-e2f7934c64e4_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_019cd2cc-7459-714b-be47-e2f7934c64e4" xlink:to="loc_srt_LitigationCaseTypeDomain_019cd2cc-7459-714b-be47-e2f7934c64e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019cd2cc-7459-76e1-84b9-710761fac9f9" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_019cd2cc-7459-714b-be47-e2f7934c64e4" xlink:to="loc_srt_LitigationCaseTypeDomain_019cd2cc-7459-76e1-84b9-710761fac9f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_019cd2cc-7459-7f7e-95fd-f55ea61ebbeb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-724f-80ca-dee7b4158827" xlink:to="loc_us-gaap_LitigationStatusAxis_019cd2cc-7459-7f7e-95fd-f55ea61ebbeb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-7f7e-95fd-f55ea61ebbeb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_019cd2cc-7459-7f7e-95fd-f55ea61ebbeb" xlink:to="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-7f7e-95fd-f55ea61ebbeb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-77d1-9e59-bf8bd81f06d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_019cd2cc-7459-7f7e-95fd-f55ea61ebbeb" xlink:to="loc_us-gaap_LitigationStatusDomain_019cd2cc-7459-77d1-9e59-bf8bd81f06d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7529-a22f-82bc73a93a7f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-724f-80ca-dee7b4158827" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7529-a22f-82bc73a93a7f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7529-a22f-82bc73a93a7f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7529-a22f-82bc73a93a7f" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7529-a22f-82bc73a93a7f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-767e-819e-56f7a1024b6f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7529-a22f-82bc73a93a7f" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-767e-819e-56f7a1024b6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyDamagesAwardedValue_019cd2cc-7459-7bf3-8c70-a6440761d324" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyDamagesAwardedValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-74c4-af26-b0e030d219e0" xlink:to="loc_us-gaap_LossContingencyDamagesAwardedValue_019cd2cc-7459-7bf3-8c70-a6440761d324" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsandContingenciesMetaldyneDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#CommitmentsandContingenciesMetaldyneDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsandContingenciesMetaldyneDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-74ba-81cf-f27e0543606c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7a07-b24d-d2e96547edc6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-74ba-81cf-f27e0543606c" xlink:to="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7a07-b24d-d2e96547edc6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-7d46-9871-23c0977b2ac7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7a07-b24d-d2e96547edc6" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-7d46-9871-23c0977b2ac7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7d46-9871-23c0977b2ac7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-7d46-9871-23c0977b2ac7" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7d46-9871-23c0977b2ac7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7879-a090-703c118b745e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-7d46-9871-23c0977b2ac7" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7879-a090-703c118b745e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_019cd2cc-7459-7ee4-88dc-dc8336a440db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7879-a090-703c118b745e" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_019cd2cc-7459-7ee4-88dc-dc8336a440db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7f15-af94-b85472c271c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7a07-b24d-d2e96547edc6" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7f15-af94-b85472c271c8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7f15-af94-b85472c271c8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7f15-af94-b85472c271c8" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7f15-af94-b85472c271c8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7e04-982d-d9df16e2011d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7f15-af94-b85472c271c8" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7e04-982d-d9df16e2011d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease_019cd2cc-7459-7672-b32a-e5e6bf735c72" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-74ba-81cf-f27e0543606c" xlink:to="loc_us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease_019cd2cc-7459-7672-b32a-e5e6bf735c72" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsandContingenciesEnvironmentalDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#CommitmentsandContingenciesEnvironmentalDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsandContingenciesEnvironmentalDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7e26-a8ad-421c96db3eb6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7231-af79-1fb1264f94d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7e26-a8ad-421c96db3eb6" xlink:to="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7231-af79-1fb1264f94d4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7c71-b121-b6b1baaae4ad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019cd2cc-7459-7231-af79-1fb1264f94d4" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7c71-b121-b6b1baaae4ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7c71-b121-b6b1baaae4ad_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7c71-b121-b6b1baaae4ad" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-7c71-b121-b6b1baaae4ad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-715a-b5eb-72f367228d85" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-7c71-b121-b6b1baaae4ad" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-715a-b5eb-72f367228d85" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalIssueMember_019cd2cc-7459-7c76-8bd7-bb274216c3c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EnvironmentalIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-715a-b5eb-72f367228d85" xlink:to="loc_us-gaap_EnvironmentalIssueMember_019cd2cc-7459-7c76-8bd7-bb274216c3c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019cd2cc-7459-780a-a7f4-da67ee60f885" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7e26-a8ad-421c96db3eb6" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019cd2cc-7459-780a-a7f4-da67ee60f885" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGross_019cd2cc-7459-7114-ab6e-72dd5d8d37dc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019cd2cc-7459-7e26-a8ad-421c96db3eb6" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGross_019cd2cc-7459-7114-ab6e-72dd5d8d37dc" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/SegmentInformationNarrativeDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#SegmentInformationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/SegmentInformationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7ec1-b698-f27abc24934b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019cd2cc-7459-749c-bea5-3fa2de315adf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7ec1-b698-f27abc24934b" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019cd2cc-7459-749c-bea5-3fa2de315adf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019cd2cc-7459-7dda-836c-96046ebc2395" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019cd2cc-7459-749c-bea5-3fa2de315adf" xlink:to="loc_srt_ConsolidationItemsAxis_019cd2cc-7459-7dda-836c-96046ebc2395" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019cd2cc-7459-7dda-836c-96046ebc2395_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019cd2cc-7459-7dda-836c-96046ebc2395" xlink:to="loc_srt_ConsolidationItemsDomain_019cd2cc-7459-7dda-836c-96046ebc2395_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019cd2cc-7459-7cc8-8742-e63745dd260b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019cd2cc-7459-7dda-836c-96046ebc2395" xlink:to="loc_srt_ConsolidationItemsDomain_019cd2cc-7459-7cc8-8742-e63745dd260b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7459-70ce-9eed-839570479bdb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019cd2cc-7459-749c-bea5-3fa2de315adf" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7459-70ce-9eed-839570479bdb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019cd2cc-7459-70ce-9eed-839570479bdb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7459-70ce-9eed-839570479bdb" xlink:to="loc_us-gaap_SegmentDomain_019cd2cc-7459-70ce-9eed-839570479bdb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019cd2cc-7459-7c8d-b168-3a1c887970f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7459-70ce-9eed-839570479bdb" xlink:to="loc_us-gaap_SegmentDomain_019cd2cc-7459-7c8d-b168-3a1c887970f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_PackagingReportableSegmentMember_019dcf37-1a04-71e3-ab61-911b04a83f54" xlink:href="trs-20260331.xsd#trs_PackagingReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019cd2cc-7459-7c8d-b168-3a1c887970f0" xlink:to="loc_trs_PackagingReportableSegmentMember_019dcf37-1a04-71e3-ab61-911b04a83f54" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsegmentsAxis_019cd2cc-7459-7f6a-a142-641458ddd0a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019cd2cc-7459-749c-bea5-3fa2de315adf" xlink:to="loc_us-gaap_SubsegmentsAxis_019cd2cc-7459-7f6a-a142-641458ddd0a4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsegmentsDomain_019cd2cc-7459-7f6a-a142-641458ddd0a4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsegmentsAxis_019cd2cc-7459-7f6a-a142-641458ddd0a4" xlink:to="loc_us-gaap_SubsegmentsDomain_019cd2cc-7459-7f6a-a142-641458ddd0a4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsegmentsDomain_019cd2cc-7459-7e5d-9a83-0dfd9c9a476a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsegmentsAxis_019cd2cc-7459-7f6a-a142-641458ddd0a4" xlink:to="loc_us-gaap_SubsegmentsDomain_019cd2cc-7459-7e5d-9a83-0dfd9c9a476a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsegmentsConsolidationItemsAxis_019cd2cc-7459-72fb-a1b0-29d0d0619814" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019cd2cc-7459-749c-bea5-3fa2de315adf" xlink:to="loc_us-gaap_SubsegmentsConsolidationItemsAxis_019cd2cc-7459-72fb-a1b0-29d0d0619814" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsegmentsConsolidationItemsDomain_019cd2cc-7459-72fb-a1b0-29d0d0619814_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsegmentsConsolidationItemsAxis_019cd2cc-7459-72fb-a1b0-29d0d0619814" xlink:to="loc_us-gaap_SubsegmentsConsolidationItemsDomain_019cd2cc-7459-72fb-a1b0-29d0d0619814_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsegmentsConsolidationItemsDomain_019cd2cc-7459-7a3f-b5c7-c97de569beb5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsegmentsConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsegmentsConsolidationItemsAxis_019cd2cc-7459-72fb-a1b0-29d0d0619814" xlink:to="loc_us-gaap_SubsegmentsConsolidationItemsDomain_019cd2cc-7459-7a3f-b5c7-c97de569beb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisAxis_019cd2cc-7459-791f-ae48-8815f6922f29" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019cd2cc-7459-749c-bea5-3fa2de315adf" xlink:to="loc_us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisAxis_019cd2cc-7459-791f-ae48-8815f6922f29" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisDomain_019cd2cc-7459-791f-ae48-8815f6922f29_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisAxis_019cd2cc-7459-791f-ae48-8815f6922f29" xlink:to="loc_us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisDomain_019cd2cc-7459-791f-ae48-8815f6922f29_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisDomain_019cd2cc-7459-7610-b805-457ec1462b4a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisAxis_019cd2cc-7459-791f-ae48-8815f6922f29" xlink:to="loc_us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisDomain_019cd2cc-7459-7610-b805-457ec1462b4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementAxis_019cd2cc-7459-79a2-8d28-07acdd95ff2a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RestatementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019cd2cc-7459-749c-bea5-3fa2de315adf" xlink:to="loc_srt_RestatementAxis_019cd2cc-7459-79a2-8d28-07acdd95ff2a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementDomain_019cd2cc-7459-79a2-8d28-07acdd95ff2a_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RestatementDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RestatementAxis_019cd2cc-7459-79a2-8d28-07acdd95ff2a" xlink:to="loc_srt_RestatementDomain_019cd2cc-7459-79a2-8d28-07acdd95ff2a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementDomain_019cd2cc-7459-7f5c-a1f4-268f6f298a1a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RestatementDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RestatementAxis_019cd2cc-7459-79a2-8d28-07acdd95ff2a" xlink:to="loc_srt_RestatementDomain_019cd2cc-7459-7f5c-a1f4-268f6f298a1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingCodmProfitLossMeasureHowUsedDescription_019cd2cc-7459-78b8-9c86-4278faaeca8f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingCodmProfitLossMeasureHowUsedDescription"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7ec1-b698-f27abc24934b" xlink:to="loc_us-gaap_SegmentReportingCodmProfitLossMeasureHowUsedDescription_019cd2cc-7459-78b8-9c86-4278faaeca8f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingCodmIndividualTitleAndPositionOrGroupOrCommitteeNameExtensibleEnumeration_019cd2cc-7459-7ddf-be07-237b98ea4def" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingCodmIndividualTitleAndPositionOrGroupOrCommitteeNameExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7ec1-b698-f27abc24934b" xlink:to="loc_us-gaap_SegmentReportingCodmIndividualTitleAndPositionOrGroupOrCommitteeNameExtensibleEnumeration_019cd2cc-7459-7ddf-be07-237b98ea4def" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_019cd300-5cfa-7b5c-b4bd-853b82518dc2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7ec1-b698-f27abc24934b" xlink:to="loc_us-gaap_NumberOfReportableSegments_019cd300-5cfa-7b5c-b4bd-853b82518dc2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_CorporateExpensesAllocatedToSegment_019dcf36-a157-7d17-8999-4d69f649b6bc" xlink:href="trs-20260331.xsd#trs_CorporateExpensesAllocatedToSegment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7ec1-b698-f27abc24934b" xlink:to="loc_trs_CorporateExpensesAllocatedToSegment_019dcf36-a157-7d17-8999-4d69f649b6bc" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/SegmentReportingSegmentActivityDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#SegmentReportingSegmentActivityDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/SegmentReportingSegmentActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019cd2cc-7459-753b-a395-f8c1a07001f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019cd2cc-7459-753b-a395-f8c1a07001f7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7459-7725-a118-5b010f14dd3a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019cd2cc-7459-753b-a395-f8c1a07001f7" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7459-7725-a118-5b010f14dd3a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019cd2cc-7459-7725-a118-5b010f14dd3a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7459-7725-a118-5b010f14dd3a" xlink:to="loc_us-gaap_SegmentDomain_019cd2cc-7459-7725-a118-5b010f14dd3a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019cd2cc-7459-7341-8595-c84389bca6f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019cd2cc-7459-7725-a118-5b010f14dd3a" xlink:to="loc_us-gaap_SegmentDomain_019cd2cc-7459-7341-8595-c84389bca6f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_PackagingReportableSegmentMember_019cd2cc-7459-7593-a759-f3e536de7bce" xlink:href="trs-20260331.xsd#trs_PackagingReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019cd2cc-7459-7341-8595-c84389bca6f7" xlink:to="loc_trs_PackagingReportableSegmentMember_019cd2cc-7459-7593-a759-f3e536de7bce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceReportableSegmentMember_019cd2cc-7459-78eb-b298-ff97235c3c4d" xlink:href="trs-20260331.xsd#trs_AerospaceReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019cd2cc-7459-7341-8595-c84389bca6f7" xlink:to="loc_trs_AerospaceReportableSegmentMember_019cd2cc-7459-78eb-b298-ff97235c3c4d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateMember_019cd2cc-7459-7c5e-831c-3f396d64740a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019cd2cc-7459-7341-8595-c84389bca6f7" xlink:to="loc_us-gaap_CorporateMember_019cd2cc-7459-7c5e-831c-3f396d64740a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SpecialtyProductsReportableSegmentMember_019cd2cc-7459-7577-9778-136efb863139" xlink:href="trs-20260331.xsd#trs_SpecialtyProductsReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019cd2cc-7459-7341-8595-c84389bca6f7" xlink:to="loc_trs_SpecialtyProductsReportableSegmentMember_019cd2cc-7459-7577-9778-136efb863139" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportableSegmentAggregationBeforeOtherOperatingSegmentMember_019cd2cc-7459-7bad-826f-3ba6e2ccfd5a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReportableSegmentAggregationBeforeOtherOperatingSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019cd2cc-7459-7341-8595-c84389bca6f7" xlink:to="loc_us-gaap_ReportableSegmentAggregationBeforeOtherOperatingSegmentMember_019cd2cc-7459-7bad-826f-3ba6e2ccfd5a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7459-7bcc-bb76-31b6b689d200" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019cd2cc-7459-753b-a395-f8c1a07001f7" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7459-7bcc-bb76-31b6b689d200" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7459-7bcc-bb76-31b6b689d200_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7459-7bcc-bb76-31b6b689d200" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7459-7bcc-bb76-31b6b689d200_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7459-7463-a957-449d78634952" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-7459-7bcc-bb76-31b6b689d200" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7459-7463-a957-449d78634952" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ArrowEngineMember_019cd2cc-7459-7cd1-94ff-aa129302251b" xlink:href="trs-20260331.xsd#trs_ArrowEngineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-7459-7463-a957-449d78634952" xlink:to="loc_trs_ArrowEngineMember_019cd2cc-7459-7cd1-94ff-aa129302251b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-797d-95ba-c08b5073217d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019cd2cc-7459-753b-a395-f8c1a07001f7" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-797d-95ba-c08b5073217d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-797d-95ba-c08b5073217d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-797d-95ba-c08b5073217d" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-797d-95ba-c08b5073217d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-71e5-b3eb-1977f11cff25" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019cd2cc-7459-797d-95ba-c08b5073217d" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-71e5-b3eb-1977f11cff25" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalIssueMember_019cd2cc-7459-7fcf-8e1b-d06da968bf2e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EnvironmentalIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-71e5-b3eb-1977f11cff25" xlink:to="loc_us-gaap_EnvironmentalIssueMember_019cd2cc-7459-7fcf-8e1b-d06da968bf2e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AsbestosIssueMember_019cd2cc-7459-7c7d-b32a-21fab365afb1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AsbestosIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019cd2cc-7459-71e5-b3eb-1977f11cff25" xlink:to="loc_us-gaap_AsbestosIssueMember_019cd2cc-7459-7c7d-b32a-21fab365afb1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019dc104-1256-72db-86cd-b536c3e276f2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementOperatingActivitiesSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019cd2cc-7459-753b-a395-f8c1a07001f7" xlink:to="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019dc104-1256-72db-86cd-b536c3e276f2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019dc104-1256-72db-86cd-b536c3e276f2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019dc104-1256-72db-86cd-b536c3e276f2" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019dc104-1256-72db-86cd-b536c3e276f2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019dc104-1256-7047-a4c2-10c1b516f97b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019dc104-1256-72db-86cd-b536c3e276f2" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019dc104-1256-7047-a4c2-10c1b516f97b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentContinuingOperationsMember_019dc104-1256-70aa-bcc9-184170caaa3b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentContinuingOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentOperatingActivitiesDomain_019dc104-1256-7047-a4c2-10c1b516f97b" xlink:to="loc_us-gaap_SegmentContinuingOperationsMember_019dc104-1256-70aa-bcc9-184170caaa3b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019cd2cc-7459-72c4-b099-5db7ac1e2fda" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_us-gaap_Revenues_019cd2cc-7459-72c4-b099-5db7ac1e2fda" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_019cd2cc-7459-7a6d-aa9c-a5ae27e85c0b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_019cd2cc-7459-7a6d-aa9c-a5ae27e85c0b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019cd2cc-7459-7ce2-91cc-51991a103773" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019cd2cc-7459-7ce2-91cc-51991a103773" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_019cd2cc-7459-78e9-bf49-3fcca914dc58" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingOtherItemAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_019cd2cc-7459-78e9-bf49-3fcca914dc58" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SegmentOperatingProfit_019cd2cc-7459-7876-acd3-af0510db6c32" xlink:href="trs-20260331.xsd#trs_SegmentOperatingProfit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_trs_SegmentOperatingProfit_019cd2cc-7459-7876-acd3-af0510db6c32" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019cd2cc-7459-7151-a123-bf2ef09a453f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_us-gaap_OperatingIncomeLoss_019cd2cc-7459-7151-a123-bf2ef09a453f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019cd2cc-7459-791e-972f-c3484ee21bd1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019cd2cc-7459-791e-972f-c3484ee21bd1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_019cd2cc-7459-70f4-a6b8-8387ec1a38df" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_019cd2cc-7459-70f4-a6b8-8387ec1a38df" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019cd2cc-7459-7a50-8708-555d24d194ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019cd2cc-7459-7a50-8708-555d24d194ff" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentSeveranceAndConsultingCosts_019cd2cc-7459-7b10-abb8-a526072cc7e7" xlink:href="trs-20260331.xsd#trs_RealignmentSeveranceAndConsultingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_trs_RealignmentSeveranceAndConsultingCosts_019cd2cc-7459-7b10-abb8-a526072cc7e7" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SystemImplementationCosts_019cd2cc-7459-71ee-b83e-612e683f9357" xlink:href="trs-20260331.xsd#trs_SystemImplementationCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_trs_SystemImplementationCosts_019cd2cc-7459-71ee-b83e-612e683f9357" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_MergersAcquisitionsDiligenceAndTransactionCosts_019cd2cc-7459-78c5-9959-13226c62f018" xlink:href="trs-20260331.xsd#trs_MergersAcquisitionsDiligenceAndTransactionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_trs_MergersAcquisitionsDiligenceAndTransactionCosts_019cd2cc-7459-78c5-9959-13226c62f018" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_019cd2cc-7459-7158-8bd5-e36641c0a826" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_019cd2cc-7459-7158-8bd5-e36641c0a826" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019cd2cc-7459-7c72-94d9-2b1fb1c0251b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019cd2cc-7459-7c72-94d9-2b1fb1c0251b" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireProductiveAssets_019cd2cc-7459-7c29-a52f-04b61a829759" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_us-gaap_PaymentsToAcquireProductiveAssets_019cd2cc-7459-7c29-a52f-04b61a829759" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_019dcf70-b628-7875-a8e8-c4cf40320581" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentExpenditureAdditionToLongLivedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_019dcf70-b628-7875-a8e8-c4cf40320581" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_019cd2cc-7459-76c2-a364-dbba1125d8de" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_019cd2cc-7459-76c2-a364-dbba1125d8de" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019cd2cc-7459-7735-ae32-404d4c973d8b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_us-gaap_Assets_019cd2cc-7459-7735-ae32-404d4c973d8b" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019dc0f6-533c-7c81-bbc6-5af96529fa43" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019dc0f6-533c-7c81-bbc6-5af96529fa43" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyReceivable_019dc0f5-edf6-710e-b935-de6f49970a68" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_us-gaap_LossContingencyReceivable_019dc0f5-edf6-710e-b935-de6f49970a68" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_OutsideBasisDifferenceOnHeldForSaleAssets_019dc0f7-ca74-745e-9f75-9e761bf02c53" xlink:href="trs-20260331.xsd#trs_OutsideBasisDifferenceOnHeldForSaleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cd2cc-7459-7a70-9f30-ab412483e405" xlink:to="loc_trs_OutsideBasisDifferenceOnHeldForSaleAssets_019dc0f7-ca74-745e-9f75-9e761bf02c53" xlink:type="arc" order="20"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityAwardsStockOptionActivityTableDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#EquityAwardsStockOptionActivityTableDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityAwardsStockOptionActivityTableDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-71d1-9f0f-dec77eb04bf2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-7166-9b0a-084412cf1f69" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-71d1-9f0f-dec77eb04bf2" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-7166-9b0a-084412cf1f69" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-7850-befc-2f2813830fbe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-7166-9b0a-084412cf1f69" xlink:to="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-7850-befc-2f2813830fbe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7850-befc-2f2813830fbe_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-7850-befc-2f2813830fbe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7850-befc-2f2813830fbe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-716b-8df9-bf142beda554" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-7850-befc-2f2813830fbe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-716b-8df9-bf142beda554" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019cd2cc-7459-7687-9a7e-eb3291b296c5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-716b-8df9-bf142beda554" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019cd2cc-7459-7687-9a7e-eb3291b296c5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_019cd2cc-7459-7630-bd3d-cb3fe56350f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-71d1-9f0f-dec77eb04bf2" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_019cd2cc-7459-7630-bd3d-cb3fe56350f7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_019cd2cc-7459-7f98-96c2-5e9f3540e889" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-71d1-9f0f-dec77eb04bf2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_019cd2cc-7459-7f98-96c2-5e9f3540e889" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityAwardsStockOptionsNarrativeDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#EquityAwardsStockOptionsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityAwardsStockOptionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7cd0-9982-7576934a3e2a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-70b0-a839-2f47903e484b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7cd0-9982-7576934a3e2a" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-70b0-a839-2f47903e484b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-7112-8cb0-d15e1146ff41" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-70b0-a839-2f47903e484b" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-7112-8cb0-d15e1146ff41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7112-8cb0-d15e1146ff41_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-7112-8cb0-d15e1146ff41" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7112-8cb0-d15e1146ff41_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7e09-a177-f449cda579d9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-7112-8cb0-d15e1146ff41" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7e09-a177-f449cda579d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_019cd2cc-7459-700c-b71f-b4491526187c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7e09-a177-f449cda579d9" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_019cd2cc-7459-700c-b71f-b4491526187c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-7f74-93f6-c601157850ef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-70b0-a839-2f47903e484b" xlink:to="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-7f74-93f6-c601157850ef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7f74-93f6-c601157850ef_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-7f74-93f6-c601157850ef" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7f74-93f6-c601157850ef_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-71bf-bcf4-fe9f49174e11" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-7f74-93f6-c601157850ef" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-71bf-bcf4-fe9f49174e11" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019cd2cc-7459-70c1-ad83-9c540764194b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-71bf-bcf4-fe9f49174e11" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019cd2cc-7459-70c1-ad83-9c540764194b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_019cd2cc-7459-7742-b9ee-6efbd51f41a0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7cd0-9982-7576934a3e2a" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_019cd2cc-7459-7742-b9ee-6efbd51f41a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019cd2cc-7459-7bf8-a493-5c04e0fb17e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7cd0-9982-7576934a3e2a" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019cd2cc-7459-7bf8-a493-5c04e0fb17e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_019cd2cc-7459-7825-ac20-97006772936d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7cd0-9982-7576934a3e2a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_019cd2cc-7459-7825-ac20-97006772936d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_StockOptionsVested_019cd2cc-7459-7c63-a216-70ba740c4b98" xlink:href="trs-20260331.xsd#trs_StockOptionsVested"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7cd0-9982-7576934a3e2a" xlink:to="loc_trs_StockOptionsVested_019cd2cc-7459-7c63-a216-70ba740c4b98" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_019cd2cc-7459-749c-88b4-4766fc82ebd6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7cd0-9982-7576934a3e2a" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_019cd2cc-7459-749c-88b4-4766fc82ebd6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019cd2cc-7459-75b9-a7f7-0ce88569a6ce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7cd0-9982-7576934a3e2a" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019cd2cc-7459-75b9-a7f7-0ce88569a6ce" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019cd2cc-7459-7378-bf10-f1c410fe3886" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7cd0-9982-7576934a3e2a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019cd2cc-7459-7378-bf10-f1c410fe3886" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019cd2cc-7459-70b8-b32a-47f54e8efa72" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7cd0-9982-7576934a3e2a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019cd2cc-7459-70b8-b32a-47f54e8efa72" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019cd2cc-7459-7e10-8fa6-61658e757865" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7cd0-9982-7576934a3e2a" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019cd2cc-7459-7e10-8fa6-61658e757865" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019cd2cc-7459-7c4b-b951-92a1e52fefd5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7cd0-9982-7576934a3e2a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019cd2cc-7459-7c4b-b951-92a1e52fefd5" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments_019cd2cc-7459-76d6-939c-17ce7de661e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7cd0-9982-7576934a3e2a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments_019cd2cc-7459-76d6-939c-17ce7de661e0" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019dd9cd-6050-7583-b1a4-36872b78f9d2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7cd0-9982-7576934a3e2a" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019dd9cd-6050-7583-b1a4-36872b78f9d2" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityAwardsRestrictedStockUnitsNarrativeDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#EquityAwardsRestrictedStockUnitsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityAwardsRestrictedStockUnitsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-73f5-9f56-77ed6dd15192" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-7dca-91a1-8006346b6aa4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-73f5-9f56-77ed6dd15192" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-7dca-91a1-8006346b6aa4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-7220-b8be-75cebae0d8ac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-7dca-91a1-8006346b6aa4" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-7220-b8be-75cebae0d8ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7220-b8be-75cebae0d8ac_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-7220-b8be-75cebae0d8ac" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-7220-b8be-75cebae0d8ac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-733c-939e-ff9d85bc02ce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cd2cc-7459-7220-b8be-75cebae0d8ac" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-733c-939e-ff9d85bc02ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_019cd2cc-7459-746f-9a61-2251f8436e6d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cd2cc-7459-733c-939e-ff9d85bc02ce" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_019cd2cc-7459-746f-9a61-2251f8436e6d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_019cd2cc-7459-7d6b-86d8-b15cc8f71bb5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-7dca-91a1-8006346b6aa4" xlink:to="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_019cd2cc-7459-7d6b-86d8-b15cc8f71bb5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_019cd2cc-7459-7d6b-86d8-b15cc8f71bb5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_019cd2cc-7459-7d6b-86d8-b15cc8f71bb5" xlink:to="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_019cd2cc-7459-7d6b-86d8-b15cc8f71bb5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_019cd2cc-7459-7cc6-817f-47263bb3223c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_019cd2cc-7459-7d6b-86d8-b15cc8f71bb5" xlink:to="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_019cd2cc-7459-7cc6-817f-47263bb3223c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationShareBasedPaymentsMember_019cd2cc-7459-7fbb-8654-8bb87d2d56a3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredCompensationShareBasedPaymentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_019cd2cc-7459-7cc6-817f-47263bb3223c" xlink:to="loc_us-gaap_DeferredCompensationShareBasedPaymentsMember_019cd2cc-7459-7fbb-8654-8bb87d2d56a3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_MetricTypeAxis_019cd2cc-7459-743e-95b5-31e6c0459225" xlink:href="trs-20260331.xsd#trs_MetricTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-7dca-91a1-8006346b6aa4" xlink:to="loc_trs_MetricTypeAxis_019cd2cc-7459-743e-95b5-31e6c0459225" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_MetricTypeDomain_019cd2cc-7459-743e-95b5-31e6c0459225_default" xlink:href="trs-20260331.xsd#trs_MetricTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_MetricTypeAxis_019cd2cc-7459-743e-95b5-31e6c0459225" xlink:to="loc_trs_MetricTypeDomain_019cd2cc-7459-743e-95b5-31e6c0459225_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_MetricTypeDomain_019cd2cc-7459-7d87-9598-a34fc356f2df" xlink:href="trs-20260331.xsd#trs_MetricTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_MetricTypeAxis_019cd2cc-7459-743e-95b5-31e6c0459225" xlink:to="loc_trs_MetricTypeDomain_019cd2cc-7459-7d87-9598-a34fc356f2df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_A3YearEpsCagrMetricMember_019cd2cc-7459-75ac-a3a7-2195d6ecdc62" xlink:href="trs-20260331.xsd#trs_A3YearEpsCagrMetricMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_MetricTypeDomain_019cd2cc-7459-7d87-9598-a34fc356f2df" xlink:to="loc_trs_A3YearEpsCagrMetricMember_019cd2cc-7459-75ac-a3a7-2195d6ecdc62" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_TotalshareholderreturnmetricMember_019cd2cc-7459-7db3-a068-c84e74b332a4" xlink:href="trs-20260331.xsd#trs_TotalshareholderreturnmetricMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_MetricTypeDomain_019cd2cc-7459-7d87-9598-a34fc356f2df" xlink:to="loc_trs_TotalshareholderreturnmetricMember_019cd2cc-7459-7db3-a068-c84e74b332a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AveragestockpriceMember_019cd2cc-7459-7022-87c2-cde316f03e53" xlink:href="trs-20260331.xsd#trs_AveragestockpriceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_MetricTypeDomain_019cd2cc-7459-7d87-9598-a34fc356f2df" xlink:to="loc_trs_AveragestockpriceMember_019cd2cc-7459-7022-87c2-cde316f03e53" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_CashReturnOnNetAssetsMetricMember_019cd2cc-7459-7a0b-b7f1-9f9a5450a78d" xlink:href="trs-20260331.xsd#trs_CashReturnOnNetAssetsMetricMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_MetricTypeDomain_019cd2cc-7459-7d87-9598-a34fc356f2df" xlink:to="loc_trs_CashReturnOnNetAssetsMetricMember_019cd2cc-7459-7a0b-b7f1-9f9a5450a78d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_EarningsPerShareCompoundAnnualGrowthRateMetricMember_019cd2cc-7459-7ad8-afdd-3cea14c95ed0" xlink:href="trs-20260331.xsd#trs_EarningsPerShareCompoundAnnualGrowthRateMetricMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_MetricTypeDomain_019cd2cc-7459-7d87-9598-a34fc356f2df" xlink:to="loc_trs_EarningsPerShareCompoundAnnualGrowthRateMetricMember_019cd2cc-7459-7ad8-afdd-3cea14c95ed0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019cd2cc-7459-7579-b431-294bd665e307" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-7dca-91a1-8006346b6aa4" xlink:to="loc_srt_RangeAxis_019cd2cc-7459-7579-b431-294bd665e307" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cd2cc-7459-7579-b431-294bd665e307_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019cd2cc-7459-7579-b431-294bd665e307" xlink:to="loc_srt_RangeMember_019cd2cc-7459-7579-b431-294bd665e307_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cd2cc-7459-7f29-bdea-a65624641b94" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019cd2cc-7459-7579-b431-294bd665e307" xlink:to="loc_srt_RangeMember_019cd2cc-7459-7f29-bdea-a65624641b94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019cd2cc-7459-780c-9ddc-88a72a679117" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cd2cc-7459-7f29-bdea-a65624641b94" xlink:to="loc_srt_MinimumMember_019cd2cc-7459-780c-9ddc-88a72a679117" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019cd2cc-7459-783b-868f-2e7a2ed174f4" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cd2cc-7459-7f29-bdea-a65624641b94" xlink:to="loc_srt_MaximumMember_019cd2cc-7459-783b-868f-2e7a2ed174f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019cd2cc-7459-700f-9a83-392dea01d8d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-7dca-91a1-8006346b6aa4" xlink:to="loc_us-gaap_PlanNameAxis_019cd2cc-7459-700f-9a83-392dea01d8d4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019cd2cc-7459-700f-9a83-392dea01d8d4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019cd2cc-7459-700f-9a83-392dea01d8d4" xlink:to="loc_us-gaap_PlanNameDomain_019cd2cc-7459-700f-9a83-392dea01d8d4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019cd2cc-7459-7119-841d-58e6908ece4c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019cd2cc-7459-700f-9a83-392dea01d8d4" xlink:to="loc_us-gaap_PlanNameDomain_019cd2cc-7459-7119-841d-58e6908ece4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan1Member_019cd2cc-7459-7ff6-b22f-dee1c4ef8877" xlink:href="trs-20260331.xsd#trs_Plan1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019cd2cc-7459-7119-841d-58e6908ece4c" xlink:to="loc_trs_Plan1Member_019cd2cc-7459-7ff6-b22f-dee1c4ef8877" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan2Member_019cd2cc-7459-73c9-98cd-5fbbdf9e093e" xlink:href="trs-20260331.xsd#trs_Plan2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019cd2cc-7459-7119-841d-58e6908ece4c" xlink:to="loc_trs_Plan2Member_019cd2cc-7459-73c9-98cd-5fbbdf9e093e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan3Member_019cd2cc-7459-7504-9fbf-cc1e55ab8999" xlink:href="trs-20260331.xsd#trs_Plan3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019cd2cc-7459-7119-841d-58e6908ece4c" xlink:to="loc_trs_Plan3Member_019cd2cc-7459-7504-9fbf-cc1e55ab8999" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan4Member_019cd2cc-7459-7223-b233-c464f4f077a9" xlink:href="trs-20260331.xsd#trs_Plan4Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019cd2cc-7459-7119-841d-58e6908ece4c" xlink:to="loc_trs_Plan4Member_019cd2cc-7459-7223-b233-c464f4f077a9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan5Member_019cd2cc-7459-7505-bb53-8978bef8699e" xlink:href="trs-20260331.xsd#trs_Plan5Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019cd2cc-7459-7119-841d-58e6908ece4c" xlink:to="loc_trs_Plan5Member_019cd2cc-7459-7505-bb53-8978bef8699e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan7Member_019cd2cc-7459-7b38-ac3e-aa9214cadac2" xlink:href="trs-20260331.xsd#trs_Plan7Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019cd2cc-7459-7119-841d-58e6908ece4c" xlink:to="loc_trs_Plan7Member_019cd2cc-7459-7b38-ac3e-aa9214cadac2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan8Member_019cd2cc-7459-7c47-b272-1a5453c70ac2" xlink:href="trs-20260331.xsd#trs_Plan8Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019cd2cc-7459-7119-841d-58e6908ece4c" xlink:to="loc_trs_Plan8Member_019cd2cc-7459-7c47-b272-1a5453c70ac2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-7656-86f8-33b583d8c475" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-7dca-91a1-8006346b6aa4" xlink:to="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-7656-86f8-33b583d8c475" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7656-86f8-33b583d8c475_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-7656-86f8-33b583d8c475" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7656-86f8-33b583d8c475_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7e1a-bc72-7086985d0978" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-7656-86f8-33b583d8c475" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7e1a-bc72-7086985d0978" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019cd2cc-7459-7a63-b2a1-3614d9ec5b52" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7e1a-bc72-7086985d0978" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019cd2cc-7459-7a63-b2a1-3614d9ec5b52" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019cd2cc-7459-74dd-b508-10918c6699f2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7e1a-bc72-7086985d0978" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019cd2cc-7459-74dd-b508-10918c6699f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_019cd2cc-7459-7b72-a042-d705a78bbcaf" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-7dca-91a1-8006346b6aa4" xlink:to="loc_srt_TitleOfIndividualAxis_019cd2cc-7459-7b72-a042-d705a78bbcaf" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019cd2cc-7459-7b72-a042-d705a78bbcaf_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_019cd2cc-7459-7b72-a042-d705a78bbcaf" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019cd2cc-7459-7b72-a042-d705a78bbcaf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019cd2cc-7459-7345-a671-d165d98db261" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_019cd2cc-7459-7b72-a042-d705a78bbcaf" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019cd2cc-7459-7345-a671-d165d98db261" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_DirectorMember_019cd2cc-7459-7be1-8760-5f3b32e6eba7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_DirectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019cd2cc-7459-7345-a671-d165d98db261" xlink:to="loc_srt_DirectorMember_019cd2cc-7459-7be1-8760-5f3b32e6eba7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsAxis_019cd2cc-7459-72a3-83b9-b1386a3d034a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-7dca-91a1-8006346b6aa4" xlink:to="loc_us-gaap_DividendsAxis_019cd2cc-7459-72a3-83b9-b1386a3d034a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_019cd2cc-7459-72a3-83b9-b1386a3d034a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DividendsAxis_019cd2cc-7459-72a3-83b9-b1386a3d034a" xlink:to="loc_us-gaap_DividendsDomain_019cd2cc-7459-72a3-83b9-b1386a3d034a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_019cd2cc-7459-7688-9514-92fa72fc387f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DividendsAxis_019cd2cc-7459-72a3-83b9-b1386a3d034a" xlink:to="loc_us-gaap_DividendsDomain_019cd2cc-7459-7688-9514-92fa72fc387f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DividendEquivalentAxisAxis_019cd2cc-7459-74c8-8051-08b9e8b4745e" xlink:href="trs-20260331.xsd#trs_DividendEquivalentAxisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-7dca-91a1-8006346b6aa4" xlink:to="loc_trs_DividendEquivalentAxisAxis_019cd2cc-7459-74c8-8051-08b9e8b4745e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DividendEquivalentAxisDomain_019cd2cc-7459-74c8-8051-08b9e8b4745e_default" xlink:href="trs-20260331.xsd#trs_DividendEquivalentAxisDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_DividendEquivalentAxisAxis_019cd2cc-7459-74c8-8051-08b9e8b4745e" xlink:to="loc_trs_DividendEquivalentAxisDomain_019cd2cc-7459-74c8-8051-08b9e8b4745e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DividendEquivalentAxisDomain_019cd2cc-7459-754f-99ac-f3cb75ee2cf8" xlink:href="trs-20260331.xsd#trs_DividendEquivalentAxisDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DividendEquivalentAxisAxis_019cd2cc-7459-74c8-8051-08b9e8b4745e" xlink:to="loc_trs_DividendEquivalentAxisDomain_019cd2cc-7459-754f-99ac-f3cb75ee2cf8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DividendEquivalentMember_019cd2cc-7459-718d-a2a0-0afc010c4ef5" xlink:href="trs-20260331.xsd#trs_DividendEquivalentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DividendEquivalentAxisDomain_019cd2cc-7459-754f-99ac-f3cb75ee2cf8" xlink:to="loc_trs_DividendEquivalentMember_019cd2cc-7459-718d-a2a0-0afc010c4ef5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued_019cd2cc-7459-7721-bc24-ad04fd6d7307" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-73f5-9f56-77ed6dd15192" xlink:to="loc_us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued_019cd2cc-7459-7721-bc24-ad04fd6d7307" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019cd2cc-7459-722b-b9c6-e379dbdb7299" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-73f5-9f56-77ed6dd15192" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019cd2cc-7459-722b-b9c6-e379dbdb7299" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_019cd2cc-7459-731e-aed5-a09e4c5fe2ef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-73f5-9f56-77ed6dd15192" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_019cd2cc-7459-731e-aed5-a09e4c5fe2ef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageEarnedBasedOnMetricOverPerformancePeriod_019cd2cc-7459-7173-81ce-91281e283418" xlink:href="trs-20260331.xsd#trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageEarnedBasedOnMetricOverPerformancePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-73f5-9f56-77ed6dd15192" xlink:to="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageEarnedBasedOnMetricOverPerformancePeriod_019cd2cc-7459-7173-81ce-91281e283418" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformancePeriodComplete_019cd2cc-7459-7c21-8af4-57c87f847a1d" xlink:href="trs-20260331.xsd#trs_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformancePeriodComplete"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-73f5-9f56-77ed6dd15192" xlink:to="loc_trs_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformancePeriodComplete_019cd2cc-7459-7c21-8af4-57c87f847a1d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019cd2cc-7459-7999-9933-abf657467c29" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-73f5-9f56-77ed6dd15192" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019cd2cc-7459-7999-9933-abf657467c29" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019cd2cc-7459-7182-af03-27f52e36d37d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-73f5-9f56-77ed6dd15192" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019cd2cc-7459-7182-af03-27f52e36d37d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfPerformanceMetricsInRestrictedSharesAwardTypePlan_019cd2cc-7459-7456-b742-52fad8447087" xlink:href="trs-20260331.xsd#trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfPerformanceMetricsInRestrictedSharesAwardTypePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-73f5-9f56-77ed6dd15192" xlink:to="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfPerformanceMetricsInRestrictedSharesAwardTypePlan_019cd2cc-7459-7456-b742-52fad8447087" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAmountOfSharesEarnedOfTargetAward_019cd2cc-7459-7f6e-b799-5eb9e13d4d92" xlink:href="trs-20260331.xsd#trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAmountOfSharesEarnedOfTargetAward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-73f5-9f56-77ed6dd15192" xlink:to="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAmountOfSharesEarnedOfTargetAward_019cd2cc-7459-7f6e-b799-5eb9e13d4d92" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageAttained_019cd2cc-7459-71f4-a3bc-de88987e3952" xlink:href="trs-20260331.xsd#trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageAttained"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-73f5-9f56-77ed6dd15192" xlink:to="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageAttained_019cd2cc-7459-71f4-a3bc-de88987e3952" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019cd2cc-7459-70e1-8c05-620f81d72b16" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-73f5-9f56-77ed6dd15192" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019cd2cc-7459-70e1-8c05-620f81d72b16" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019cd2cc-7459-7b2f-832d-49eea9008e4b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-73f5-9f56-77ed6dd15192" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019cd2cc-7459-7b2f-832d-49eea9008e4b" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019cd2cc-7459-76d2-a2a5-d42e7771f039" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-73f5-9f56-77ed6dd15192" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019cd2cc-7459-76d2-a2a5-d42e7771f039" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019cd2cc-7459-7a8b-a636-b26602392012" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-73f5-9f56-77ed6dd15192" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019cd2cc-7459-7a8b-a636-b26602392012" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityAwardsRestrictedStockUnitsActivityTableDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#EquityAwardsRestrictedStockUnitsActivityTableDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityAwardsRestrictedStockUnitsActivityTableDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7686-aa5c-a7299fe88c7e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-7422-8082-a4948912df01" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7686-aa5c-a7299fe88c7e" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-7422-8082-a4948912df01" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-76e6-bb86-b86cf6768e6f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cd2cc-7459-7422-8082-a4948912df01" xlink:to="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-76e6-bb86-b86cf6768e6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-76e6-bb86-b86cf6768e6f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-76e6-bb86-b86cf6768e6f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-76e6-bb86-b86cf6768e6f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7b97-8c23-233f0813097d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-76e6-bb86-b86cf6768e6f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7b97-8c23-233f0813097d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019cd2cc-7459-78fa-b782-9ae0fc54dd9e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7b97-8c23-233f0813097d" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019cd2cc-7459-78fa-b782-9ae0fc54dd9e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019cd2cc-7459-7c67-9697-d9d59a416ea1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7686-aa5c-a7299fe88c7e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019cd2cc-7459-7c67-9697-d9d59a416ea1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019cd2cc-7459-74c3-8e47-5ebd450df15f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019cd2cc-7459-7c67-9697-d9d59a416ea1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019cd2cc-7459-74c3-8e47-5ebd450df15f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SharebasedCompensationArrangementbySharebasedPaymentAwardOtherThanOptionsSpinoffAdjustment_019cd2cc-7459-774d-9910-b0550c446394" xlink:href="trs-20260331.xsd#trs_SharebasedCompensationArrangementbySharebasedPaymentAwardOtherThanOptionsSpinoffAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019cd2cc-7459-7c67-9697-d9d59a416ea1" xlink:to="loc_trs_SharebasedCompensationArrangementbySharebasedPaymentAwardOtherThanOptionsSpinoffAdjustment_019cd2cc-7459-774d-9910-b0550c446394" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019cd2cc-7459-7256-9935-65f6c5fa88cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019cd2cc-7459-7c67-9697-d9d59a416ea1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019cd2cc-7459-7256-9935-65f6c5fa88cc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019cd2cc-7459-7e86-909c-66206dc43140" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019cd2cc-7459-7c67-9697-d9d59a416ea1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019cd2cc-7459-7e86-909c-66206dc43140" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019cd2cc-7459-7bf1-bff6-5388e4abc22c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019cd2cc-7459-7c67-9697-d9d59a416ea1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019cd2cc-7459-7bf1-bff6-5388e4abc22c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019cd2cc-7459-76d4-9672-1b9a79c8b0d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019cd2cc-7459-77bc-a059-663d0b8310ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7686-aa5c-a7299fe88c7e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019cd2cc-7459-77bc-a059-663d0b8310ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019cd2cc-7459-7f6c-884a-b00140c64120" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019cd2cc-7459-77bc-a059-663d0b8310ba" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019cd2cc-7459-7f6c-884a-b00140c64120" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019cd2cc-7459-7898-adbd-6c981f09b230" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019cd2cc-7459-77bc-a059-663d0b8310ba" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019cd2cc-7459-7898-adbd-6c981f09b230" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019cd2cc-7459-7743-9be1-6e199fa13847" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019cd2cc-7459-77bc-a059-663d0b8310ba" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019cd2cc-7459-7743-9be1-6e199fa13847" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019cd2cc-7459-7416-aa4c-7453f64e7105" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019cd2cc-7459-77bc-a059-663d0b8310ba" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019cd2cc-7459-7416-aa4c-7453f64e7105" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019cd2cc-7459-77c0-a7d3-9441a3e3ab1e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019cd2cc-7459-7b77-b33f-d0d8f041ff7d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cd2cc-7459-7686-aa5c-a7299fe88c7e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019cd2cc-7459-7b77-b33f-d0d8f041ff7d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_019cd2cc-7459-727e-bf8c-92a24cd57bb5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019cd2cc-7459-7b77-b33f-d0d8f041ff7d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_019cd2cc-7459-727e-bf8c-92a24cd57bb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedIntrinsicValue_019cd2cc-7459-7482-ae0d-61dd1b326d57" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019cd2cc-7459-7b77-b33f-d0d8f041ff7d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedIntrinsicValue_019cd2cc-7459-7482-ae0d-61dd1b326d57" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/EarningsperShareEarningsperShareDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#EarningsperShareEarningsperShareDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EarningsperShareEarningsperShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDilutedLineItems_019cd2cc-7459-7c42-9e15-5a8ad0ec879c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareDilutedLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_019cd2cc-7459-7497-b01c-744a5f1becda" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_019cd2cc-7459-7c42-9e15-5a8ad0ec879c" xlink:to="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_019cd2cc-7459-7497-b01c-744a5f1becda" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-7a85-ac1f-95ee0ddd8dc1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_019cd2cc-7459-7497-b01c-744a5f1becda" xlink:to="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-7a85-ac1f-95ee0ddd8dc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7a85-ac1f-95ee0ddd8dc1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-7a85-ac1f-95ee0ddd8dc1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7a85-ac1f-95ee0ddd8dc1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7583-8306-823f1f6a44e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019cd2cc-7459-7a85-ac1f-95ee0ddd8dc1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7583-8306-823f1f6a44e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019cd2cc-7459-7106-9a39-3e13b26398da" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7583-8306-823f1f6a44e2" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019cd2cc-7459-7106-9a39-3e13b26398da" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019cd2cc-7459-79df-8b61-72288cb9bfd6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cd2cc-7459-7583-8306-823f1f6a44e2" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019cd2cc-7459-79df-8b61-72288cb9bfd6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019cd2cc-7459-7f60-a2e2-9cda3311aeee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_019cd2cc-7459-7c42-9e15-5a8ad0ec879c" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019cd2cc-7459-7f60-a2e2-9cda3311aeee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019cd2cc-7459-7ca9-bc11-bb6e0c9845be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_019cd2cc-7459-7c42-9e15-5a8ad0ec879c" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019cd2cc-7459-7ca9-bc11-bb6e0c9845be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019cd2cc-7459-79cf-ae14-f921bda2cf2d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_019cd2cc-7459-7c42-9e15-5a8ad0ec879c" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019cd2cc-7459-79cf-ae14-f921bda2cf2d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019cd2cc-7459-7f6c-9023-d9dbdafe217b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_019cd2cc-7459-7c42-9e15-5a8ad0ec879c" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019cd2cc-7459-7f6c-9023-d9dbdafe217b" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/EarningsperShareRepurchaseofCommonStockDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#EarningsperShareRepurchaseofCommonStockDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EarningsperShareRepurchaseofCommonStockDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019cd2cc-7459-792d-bc45-44c462a5c1b3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ShareRepurchaseProgramTable_019cd2cc-7459-7cd4-a9fe-567bf24b843a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ShareRepurchaseProgramTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7459-792d-bc45-44c462a5c1b3" xlink:to="loc_srt_ShareRepurchaseProgramTable_019cd2cc-7459-7cd4-a9fe-567bf24b843a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ShareRepurchaseProgramAxis_019cd2cc-7459-7ba1-9efc-2eaaf4a9bc11" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ShareRepurchaseProgramAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_ShareRepurchaseProgramTable_019cd2cc-7459-7cd4-a9fe-567bf24b843a" xlink:to="loc_srt_ShareRepurchaseProgramAxis_019cd2cc-7459-7ba1-9efc-2eaaf4a9bc11" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ShareRepurchaseProgramDomain_019cd2cc-7459-7ba1-9efc-2eaaf4a9bc11_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ShareRepurchaseProgramAxis_019cd2cc-7459-7ba1-9efc-2eaaf4a9bc11" xlink:to="loc_srt_ShareRepurchaseProgramDomain_019cd2cc-7459-7ba1-9efc-2eaaf4a9bc11_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ShareRepurchaseProgramDomain_019cd2cc-7459-77df-9ead-2d0de827c297" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ShareRepurchaseProgramAxis_019cd2cc-7459-7ba1-9efc-2eaaf4a9bc11" xlink:to="loc_srt_ShareRepurchaseProgramDomain_019cd2cc-7459-77df-9ead-2d0de827c297" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_A10b51sharerepurchaseprogramMember_019cd2cc-7459-7bb7-b5d3-b22796c4ef29" xlink:href="trs-20260331.xsd#trs_A10b51sharerepurchaseprogramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ShareRepurchaseProgramDomain_019cd2cc-7459-77df-9ead-2d0de827c297" xlink:to="loc_trs_A10b51sharerepurchaseprogramMember_019cd2cc-7459-7bb7-b5d3-b22796c4ef29" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_019cd2cc-7459-7481-8eda-b1d195ae6ff7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7459-792d-bc45-44c462a5c1b3" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_019cd2cc-7459-7481-8eda-b1d195ae6ff7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019cd2cc-7459-7752-a53b-11c09fcf5395" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7459-792d-bc45-44c462a5c1b3" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019cd2cc-7459-7752-a53b-11c09fcf5395" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019cd2cc-7459-754f-bf92-a6b44baa10e4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7459-792d-bc45-44c462a5c1b3" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019cd2cc-7459-754f-bf92-a6b44baa10e4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_019cd2cc-7459-70b3-b2ba-27b5f4e57e00" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cd2cc-7459-792d-bc45-44c462a5c1b3" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_019cd2cc-7459-70b3-b2ba-27b5f4e57e00" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DefinedBenefitPlansNetPeriodicPensionCostsDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#DefinedBenefitPlansNetPeriodicPensionCostsDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DefinedBenefitPlansNetPeriodicPensionCostsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019cd2cc-7459-7276-8d01-5b76c0fd9041" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_019cd2cc-7459-731f-8185-a1200c40f7d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019cd2cc-7459-7276-8d01-5b76c0fd9041" xlink:to="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_019cd2cc-7459-731f-8185-a1200c40f7d1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_019cd2cc-7459-7f5b-8368-a9d91c63216b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_019cd2cc-7459-731f-8185-a1200c40f7d1" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_019cd2cc-7459-7f5b-8368-a9d91c63216b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_019cd2cc-7459-7f5b-8368-a9d91c63216b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_019cd2cc-7459-7f5b-8368-a9d91c63216b" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_019cd2cc-7459-7f5b-8368-a9d91c63216b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_019cd2cc-7459-7477-aff3-c07da74578de" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_019cd2cc-7459-7f5b-8368-a9d91c63216b" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_019cd2cc-7459-7477-aff3-c07da74578de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_019cd2cc-7459-7c6a-9db3-01f4df0f188a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_019cd2cc-7459-7477-aff3-c07da74578de" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_019cd2cc-7459-7c6a-9db3-01f4df0f188a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_019cd2cc-7459-7cd0-ab7e-c4c5be50b1ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_019cd2cc-7459-7477-aff3-c07da74578de" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_019cd2cc-7459-7cd0-ab7e-c4c5be50b1ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019dc0f9-be4a-7ddc-bbea-a0e1fabc4ce7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementOperatingActivitiesSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_019cd2cc-7459-731f-8185-a1200c40f7d1" xlink:to="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019dc0f9-be4a-7ddc-bbea-a0e1fabc4ce7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019dc0f9-be4a-7ddc-bbea-a0e1fabc4ce7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019dc0f9-be4a-7ddc-bbea-a0e1fabc4ce7" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019dc0f9-be4a-7ddc-bbea-a0e1fabc4ce7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019dc0f9-be4a-7218-8d76-bae4ef6da2b7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019dc0f9-be4a-7ddc-bbea-a0e1fabc4ce7" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019dc0f9-be4a-7218-8d76-bae4ef6da2b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDiscontinuedOperationsMember_019dc0f9-be4a-70f2-b176-6e9044a74f5a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentOperatingActivitiesDomain_019dc0f9-be4a-7218-8d76-bae4ef6da2b7" xlink:to="loc_us-gaap_SegmentDiscontinuedOperationsMember_019dc0f9-be4a-70f2-b176-6e9044a74f5a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_019cd2cc-7459-732a-83a2-489af717c2dc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019cd2cc-7459-7276-8d01-5b76c0fd9041" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_019cd2cc-7459-732a-83a2-489af717c2dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_019cd2cc-7459-72df-b079-da90164085f2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019cd2cc-7459-7276-8d01-5b76c0fd9041" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_019cd2cc-7459-72df-b079-da90164085f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_019cd2cc-7459-7773-b304-776b124a05f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019cd2cc-7459-7276-8d01-5b76c0fd9041" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_019cd2cc-7459-7773-b304-776b124a05f9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_019cd2cc-7459-7951-b96f-8a0b93b4963f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019cd2cc-7459-7276-8d01-5b76c0fd9041" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_019cd2cc-7459-7951-b96f-8a0b93b4963f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_019cd2cc-7459-79eb-b4ec-674aa7e1facf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019cd2cc-7459-7276-8d01-5b76c0fd9041" xlink:to="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_019cd2cc-7459-79eb-b4ec-674aa7e1facf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_019cd2cc-7459-7f4a-a0a6-779f9b9d7563" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019cd2cc-7459-7276-8d01-5b76c0fd9041" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_019cd2cc-7459-7f4a-a0a6-779f9b9d7563" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_019cd2cc-7459-7451-97c0-e90d02d310e3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019cd2cc-7459-7276-8d01-5b76c0fd9041" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_019cd2cc-7459-7451-97c0-e90d02d310e3" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DefinedBenefitPlansDefinedBenefitPlansNarrativeDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#DefinedBenefitPlansDefinedBenefitPlansNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DefinedBenefitPlansDefinedBenefitPlansNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019cd2cc-7459-7a1b-9159-cb906bdf861d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_019cd2cc-7459-79e9-b9c1-5dcb3c23b55f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019cd2cc-7459-7a1b-9159-cb906bdf861d" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_019cd2cc-7459-79e9-b9c1-5dcb3c23b55f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_019cd2cc-7459-7694-b9ce-cedb50fb0119" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_019cd2cc-7459-79e9-b9c1-5dcb3c23b55f" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_019cd2cc-7459-7694-b9ce-cedb50fb0119" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_019cd2cc-7459-7694-b9ce-cedb50fb0119_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_019cd2cc-7459-7694-b9ce-cedb50fb0119" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_019cd2cc-7459-7694-b9ce-cedb50fb0119_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_019cd2cc-7459-7007-b582-acb940bbd6ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_019cd2cc-7459-7694-b9ce-cedb50fb0119" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_019cd2cc-7459-7007-b582-acb940bbd6ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_019cd2cc-7459-7a23-aaab-5809d77f881b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_019cd2cc-7459-7007-b582-acb940bbd6ff" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_019cd2cc-7459-7a23-aaab-5809d77f881b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationAxis_019cd2cc-7459-7908-b5be-a7309a29b4fa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanSponsorLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_019cd2cc-7459-79e9-b9c1-5dcb3c23b55f" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationAxis_019cd2cc-7459-7908-b5be-a7309a29b4fa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationDomain_019cd2cc-7459-7908-b5be-a7309a29b4fa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanSponsorLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationAxis_019cd2cc-7459-7908-b5be-a7309a29b4fa" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationDomain_019cd2cc-7459-7908-b5be-a7309a29b4fa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationDomain_019cd2cc-7459-744a-b979-e4517521c264" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanSponsorLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationAxis_019cd2cc-7459-7908-b5be-a7309a29b4fa" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationDomain_019cd2cc-7459-744a-b979-e4517521c264" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignPlanMember_019cd2cc-7459-732c-8966-31a328f33a27" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationDomain_019cd2cc-7459-744a-b979-e4517521c264" xlink:to="loc_us-gaap_ForeignPlanMember_019cd2cc-7459-732c-8966-31a328f33a27" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_GB_019cd2cc-7459-744d-9e4b-1915701a95d1" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_GB"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ForeignPlanMember_019cd2cc-7459-732c-8966-31a328f33a27" xlink:to="loc_country_GB_019cd2cc-7459-744d-9e4b-1915701a95d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_019cd2cc-7459-7dab-9703-911b5ee1092a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019cd2cc-7459-7a1b-9159-cb906bdf861d" xlink:to="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_019cd2cc-7459-7dab-9703-911b5ee1092a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_019cd2cc-745a-73cf-9551-3038d6d2ec59" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019cd2cc-7459-7a1b-9159-cb906bdf861d" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_019cd2cc-745a-73cf-9551-3038d6d2ec59" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsRemainderOfFiscalYear_019cd2cc-745a-7acc-9ef4-099863ec2755" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsRemainderOfFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019cd2cc-7459-7a1b-9159-cb906bdf861d" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsRemainderOfFiscalYear_019cd2cc-745a-7acc-9ef4-099863ec2755" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityOfferingDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#EquityOfferingDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityOfferingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_019cd2cc-745a-7dcd-82a6-c5b827df9efe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_019cd2cc-745a-7d7e-9f41-4c35c81c1786" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_019cd2cc-745a-7dcd-82a6-c5b827df9efe" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_019cd2cc-745a-7d7e-9f41-4c35c81c1786" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_019cd2cc-745a-790e-85d0-0fa152d7c475" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_019cd2cc-745a-7d7e-9f41-4c35c81c1786" xlink:to="loc_us-gaap_StatementClassOfStockAxis_019cd2cc-745a-790e-85d0-0fa152d7c475" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019cd2cc-745a-790e-85d0-0fa152d7c475_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019cd2cc-745a-790e-85d0-0fa152d7c475" xlink:to="loc_us-gaap_ClassOfStockDomain_019cd2cc-745a-790e-85d0-0fa152d7c475_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019cd2cc-745a-7419-9c8b-0b1d2de38071" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019cd2cc-745a-790e-85d0-0fa152d7c475" xlink:to="loc_us-gaap_ClassOfStockDomain_019cd2cc-745a-7419-9c8b-0b1d2de38071" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019cd2cc-745a-7ab1-b0cf-4ad4d0a2cd9f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019cd2cc-745a-7419-9c8b-0b1d2de38071" xlink:to="loc_us-gaap_CommonStockMember_019cd2cc-745a-7ab1-b0cf-4ad4d0a2cd9f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_019cd2cc-745a-7ba4-821a-add0f407d939" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019cd2cc-745a-7dcd-82a6-c5b827df9efe" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_019cd2cc-745a-7ba4-821a-add0f407d939" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockPricePerShare_019cd2cc-745a-7872-8ae3-2881db12dc10" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SaleOfStockPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019cd2cc-745a-7dcd-82a6-c5b827df9efe" xlink:to="loc_us-gaap_SaleOfStockPricePerShare_019cd2cc-745a-7872-8ae3-2881db12dc10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfStockIssuanceCosts_019cd2cc-745a-7a6a-a12a-0ca8243321f3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfStockIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019cd2cc-745a-7dcd-82a6-c5b827df9efe" xlink:to="loc_us-gaap_PaymentsOfStockIssuanceCosts_019cd2cc-745a-7a6a-a12a-0ca8243321f3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_019cd2cc-745a-762b-8492-65a2c9b320c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019cd2cc-745a-7dcd-82a6-c5b827df9efe" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_019cd2cc-745a-762b-8492-65a2c9b320c7" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/OtherComprehensiveIncomeLossDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#OtherComprehensiveIncomeLossDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/OtherComprehensiveIncomeLossDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019cd2cc-745a-7093-ae14-56433d1ea974" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019cd2cc-745a-7c93-a70e-1988375af666" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019cd2cc-745a-7093-ae14-56433d1ea974" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019cd2cc-745a-7c93-a70e-1988375af666" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019cd2cc-745a-79f6-b29e-b96044b6d1d9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019cd2cc-745a-7c93-a70e-1988375af666" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019cd2cc-745a-79f6-b29e-b96044b6d1d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019cd2cc-745a-79f6-b29e-b96044b6d1d9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019cd2cc-745a-79f6-b29e-b96044b6d1d9" xlink:to="loc_us-gaap_EquityComponentDomain_019cd2cc-745a-79f6-b29e-b96044b6d1d9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019cd2cc-745a-7458-afc7-cf595f774ac2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019cd2cc-745a-79f6-b29e-b96044b6d1d9" xlink:to="loc_us-gaap_EquityComponentDomain_019cd2cc-745a-7458-afc7-cf595f774ac2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_019cd2cc-745a-7a5f-9285-bba2a46e27c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019cd2cc-745a-7458-afc7-cf595f774ac2" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_019cd2cc-745a-7a5f-9285-bba2a46e27c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AccumulatedNetGainLossfromHedgesAttributabletoParentMember_019cd2cc-745a-7174-b8df-3c7f78e15597" xlink:href="trs-20260331.xsd#trs_AccumulatedNetGainLossfromHedgesAttributabletoParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019cd2cc-745a-7458-afc7-cf595f774ac2" xlink:to="loc_trs_AccumulatedNetGainLossfromHedgesAttributabletoParentMember_019cd2cc-745a-7174-b8df-3c7f78e15597" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019cd2cc-745a-7a1f-a6c1-055a753b8618" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019cd2cc-745a-7458-afc7-cf595f774ac2" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019cd2cc-745a-7a1f-a6c1-055a753b8618" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019cd2cc-745a-7980-84e8-5d3dd56a2c81" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019cd2cc-745a-7458-afc7-cf595f774ac2" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019cd2cc-745a-7980-84e8-5d3dd56a2c81" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-745a-7e28-bcfd-ce24f6f0409c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019cd2cc-745a-7c93-a70e-1988375af666" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-745a-7e28-bcfd-ce24f6f0409c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-745a-7e28-bcfd-ce24f6f0409c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-745a-7e28-bcfd-ce24f6f0409c" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-745a-7e28-bcfd-ce24f6f0409c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-745a-7424-bbba-42e2879349eb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-745a-7e28-bcfd-ce24f6f0409c" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-745a-7424-bbba-42e2879349eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019cd2cc-745a-77e8-9723-5a1fa5392a89" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-745a-7424-bbba-42e2879349eb" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019cd2cc-745a-77e8-9723-5a1fa5392a89" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019cd2cc-745a-7f6d-b4d4-9c4c8daa2e9b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AOCIAttributableToParentNetOfTaxRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019cd2cc-745a-7093-ae14-56433d1ea974" xlink:to="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019cd2cc-745a-7f6d-b4d4-9c4c8daa2e9b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019cd2cc-745a-7d99-bf6a-c9283151ca02" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019cd2cc-745a-7f6d-b4d4-9c4c8daa2e9b" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019cd2cc-745a-7d99-bf6a-c9283151ca02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_019cd2cc-745a-7b08-85bd-d3d5597e2cb5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019cd2cc-745a-7f6d-b4d4-9c4c8daa2e9b" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_019cd2cc-745a-7b08-85bd-d3d5597e2cb5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019cd2cc-745a-7f23-9411-e6fd178ca2f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019cd2cc-745a-7f6d-b4d4-9c4c8daa2e9b" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019cd2cc-745a-7f23-9411-e6fd178ca2f7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019cd2cc-745a-7ad6-96cd-d26e0f215141" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019cd2cc-745a-7f6d-b4d4-9c4c8daa2e9b" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019cd2cc-745a-7ad6-96cd-d26e0f215141" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Reclassificationofstrandedtaxeffects_019cd2cc-745a-75d0-aa31-5e833eca3178" xlink:href="trs-20260331.xsd#trs_Reclassificationofstrandedtaxeffects"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019cd2cc-745a-7f6d-b4d4-9c4c8daa2e9b" xlink:to="loc_trs_Reclassificationofstrandedtaxeffects_019cd2cc-745a-75d0-aa31-5e833eca3178" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019cd2cc-745a-717f-bcd7-48ce6ff95f59" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTaxAbstract_019cd2cc-745a-7e75-b370-be6149b00cd1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019cd2cc-745a-7093-ae14-56433d1ea974" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTaxAbstract_019cd2cc-745a-7e75-b370-be6149b00cd1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTax_019cd2cc-745a-7ed0-89a1-040c3c8c7c2d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019cd2cc-745a-7093-ae14-56433d1ea974" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTax_019cd2cc-745a-7ed0-89a1-040c3c8c7c2d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBeforeReclassificationAdjustmentsTax_019dcf3c-d296-7e53-a769-17db31fe5502" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBeforeReclassificationAdjustmentsTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019cd2cc-745a-7093-ae14-56433d1ea974" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBeforeReclassificationAdjustmentsTax_019dcf3c-d296-7e53-a769-17db31fe5502" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax_019dcf3d-952b-746c-8a7d-28bc69e6e708" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019cd2cc-745a-7093-ae14-56433d1ea974" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax_019dcf3d-952b-746c-8a7d-28bc69e6e708" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/IncomeTaxesDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#IncomeTaxesDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/IncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019cd2cc-745a-7f51-ae31-ab6de396f2cf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_019cd2cc-745a-7dcd-be3c-8f8d7cd9065d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019cd2cc-745a-7f51-ae31-ab6de396f2cf" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_019cd2cc-745a-7dcd-be3c-8f8d7cd9065d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-745a-736a-8d03-982d53801bab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_019cd2cc-745a-7dcd-be3c-8f8d7cd9065d" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-745a-736a-8d03-982d53801bab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-745a-736a-8d03-982d53801bab_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-745a-736a-8d03-982d53801bab" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-745a-736a-8d03-982d53801bab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-745a-77d7-b26b-e07105a7d07b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019cd2cc-745a-736a-8d03-982d53801bab" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-745a-77d7-b26b-e07105a7d07b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ArrowEngineMember_019cd2cc-745a-7114-9063-0194e9f14da0" xlink:href="trs-20260331.xsd#trs_ArrowEngineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019cd2cc-745a-77d7-b26b-e07105a7d07b" xlink:to="loc_trs_ArrowEngineMember_019cd2cc-745a-7114-9063-0194e9f14da0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019cd2cc-745a-7b70-b659-c6cc84972675" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019cd2cc-745a-7f51-ae31-ab6de396f2cf" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019cd2cc-745a-7b70-b659-c6cc84972675" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ReclassificationOfDeferredTaxBenefitsAerospaceDivestiture_019dcf41-0a3a-7bdc-9497-2f25bc00a44f" xlink:href="trs-20260331.xsd#trs_ReclassificationOfDeferredTaxBenefitsAerospaceDivestiture"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019cd2cc-745a-7f51-ae31-ab6de396f2cf" xlink:to="loc_trs_ReclassificationOfDeferredTaxBenefitsAerospaceDivestiture_019dcf41-0a3a-7bdc-9497-2f25bc00a44f" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/SubsequentEventDividendDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#SubsequentEventDividendDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/SubsequentEventDividendDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-73a9-8e97-90973f0fefd4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_019cd2cc-745a-7e50-8da3-a361923fa9fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-73a9-8e97-90973f0fefd4" xlink:to="loc_us-gaap_SubsequentEventTable_019cd2cc-745a-7e50-8da3-a361923fa9fe" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019cd2cc-745a-78d7-a8de-19fac002c9ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019cd2cc-745a-7e50-8da3-a361923fa9fe" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019cd2cc-745a-78d7-a8de-19fac002c9ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-78d7-a8de-19fac002c9ae_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019cd2cc-745a-78d7-a8de-19fac002c9ae" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-78d7-a8de-19fac002c9ae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-7fbf-ba1e-5b92d33c6bba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019cd2cc-745a-78d7-a8de-19fac002c9ae" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-7fbf-ba1e-5b92d33c6bba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019cd2cc-745a-727e-824b-e6302fea2658" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-7fbf-ba1e-5b92d33c6bba" xlink:to="loc_us-gaap_SubsequentEventMember_019cd2cc-745a-727e-824b-e6302fea2658" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsAxis_019cd2cc-745a-7e8c-bd7d-104aa2e4b54a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019cd2cc-745a-7e50-8da3-a361923fa9fe" xlink:to="loc_us-gaap_DividendsAxis_019cd2cc-745a-7e8c-bd7d-104aa2e4b54a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_019cd2cc-745a-7e8c-bd7d-104aa2e4b54a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DividendsAxis_019cd2cc-745a-7e8c-bd7d-104aa2e4b54a" xlink:to="loc_us-gaap_DividendsDomain_019cd2cc-745a-7e8c-bd7d-104aa2e4b54a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_019cd2cc-745a-7462-9c40-fd84c1c84829" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DividendsAxis_019cd2cc-745a-7e8c-bd7d-104aa2e4b54a" xlink:to="loc_us-gaap_DividendsDomain_019cd2cc-745a-7462-9c40-fd84c1c84829" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_O2025Q2DividendsMember_019cd2cc-745a-781d-a679-7b6c6e6a56ad" xlink:href="trs-20260331.xsd#trs_O2025Q2DividendsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DividendsDomain_019cd2cc-745a-7462-9c40-fd84c1c84829" xlink:to="loc_trs_O2025Q2DividendsMember_019cd2cc-745a-781d-a679-7b6c6e6a56ad" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_O2026Q2DividendsMember_019cd2cc-745a-72ee-a91e-30441fca3a72" xlink:href="trs-20260331.xsd#trs_O2026Q2DividendsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DividendsDomain_019cd2cc-745a-7462-9c40-fd84c1c84829" xlink:to="loc_trs_O2026Q2DividendsMember_019cd2cc-745a-72ee-a91e-30441fca3a72" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableAmountPerShare_019cd2cc-745a-7aa3-8a15-b0eece219cc7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsPayableAmountPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-73a9-8e97-90973f0fefd4" xlink:to="loc_us-gaap_DividendsPayableAmountPerShare_019cd2cc-745a-7aa3-8a15-b0eece219cc7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableDateDeclaredDayMonthAndYear_019cd2cc-745a-7a72-af25-857deddb5db8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsPayableDateDeclaredDayMonthAndYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-73a9-8e97-90973f0fefd4" xlink:to="loc_us-gaap_DividendsPayableDateDeclaredDayMonthAndYear_019cd2cc-745a-7a72-af25-857deddb5db8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendPayableDateToBePaidDayMonthAndYear_019cd2cc-745a-72fc-94e1-b1b457e4125c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendPayableDateToBePaidDayMonthAndYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-73a9-8e97-90973f0fefd4" xlink:to="loc_us-gaap_DividendPayableDateToBePaidDayMonthAndYear_019cd2cc-745a-72fc-94e1-b1b457e4125c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableDateOfRecordDayMonthAndYear_019cd2cc-745a-7c29-bc8b-88d5d4c416fa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsPayableDateOfRecordDayMonthAndYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-73a9-8e97-90973f0fefd4" xlink:to="loc_us-gaap_DividendsPayableDateOfRecordDayMonthAndYear_019cd2cc-745a-7c29-bc8b-88d5d4c416fa" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/SubsequentEventCrossCurrencySwapDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#SubsequentEventCrossCurrencySwapDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/SubsequentEventCrossCurrencySwapDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-70a8-8195-df0ce0b281e3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_019cd2cc-745a-71bb-82e9-300e5c268214" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-70a8-8195-df0ce0b281e3" xlink:to="loc_us-gaap_SubsequentEventTable_019cd2cc-745a-71bb-82e9-300e5c268214" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-745a-76d9-8b88-edbcac254dc1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019cd2cc-745a-71bb-82e9-300e5c268214" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-745a-76d9-8b88-edbcac254dc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-745a-76d9-8b88-edbcac254dc1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-745a-76d9-8b88-edbcac254dc1" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-745a-76d9-8b88-edbcac254dc1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-745a-777a-93f4-61dac047bf1b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd2cc-745a-76d9-8b88-edbcac254dc1" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-745a-777a-93f4-61dac047bf1b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019cd2cc-745a-731d-a962-8fef14018c10" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019cd2cc-745a-777a-93f4-61dac047bf1b" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019cd2cc-745a-731d-a962-8fef14018c10" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-745a-763a-94e6-53f8e9a137f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019cd2cc-745a-71bb-82e9-300e5c268214" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-745a-763a-94e6-53f8e9a137f7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-745a-763a-94e6-53f8e9a137f7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-745a-763a-94e6-53f8e9a137f7" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-745a-763a-94e6-53f8e9a137f7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-745a-7674-8fc5-6e5d0970f9ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd2cc-745a-763a-94e6-53f8e9a137f7" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-745a-7674-8fc5-6e5d0970f9ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019cd2cc-745a-71f7-8cf4-587e74ed2b70" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019cd2cc-745a-7674-8fc5-6e5d0970f9ed" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019cd2cc-745a-71f7-8cf4-587e74ed2b70" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019cd2cc-745a-7ef4-923d-9aa284bb0895" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019cd2cc-745a-71bb-82e9-300e5c268214" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019cd2cc-745a-7ef4-923d-9aa284bb0895" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-7ef4-923d-9aa284bb0895_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019cd2cc-745a-7ef4-923d-9aa284bb0895" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-7ef4-923d-9aa284bb0895_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-7fc3-b12f-628bf69c7f01" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019cd2cc-745a-7ef4-923d-9aa284bb0895" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-7fc3-b12f-628bf69c7f01" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019cd2cc-745a-73ad-8551-c29d9edf55d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-7fc3-b12f-628bf69c7f01" xlink:to="loc_us-gaap_SubsequentEventMember_019cd2cc-745a-73ad-8551-c29d9edf55d0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DerivativeNotionalAmountToBeSettled_019cd2cc-745a-7c71-bef1-a841636ca234" xlink:href="trs-20260331.xsd#trs_DerivativeNotionalAmountToBeSettled"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-70a8-8195-df0ce0b281e3" xlink:to="loc_trs_DerivativeNotionalAmountToBeSettled_019cd2cc-745a-7c71-bef1-a841636ca234" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_019cd2cc-745a-70df-a98b-dd83e464d28b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-70a8-8195-df0ce0b281e3" xlink:to="loc_us-gaap_DerivativeNotionalAmount_019cd2cc-745a-70df-a98b-dd83e464d28b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFixedInterestRate_019cd2cc-745a-7e0e-bc4b-c089f4f21158" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFixedInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-70a8-8195-df0ce0b281e3" xlink:to="loc_us-gaap_DerivativeFixedInterestRate_019cd2cc-745a-7e0e-bc4b-c089f4f21158" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_CashProceedsExpectedOnSettlementOfDerivative_019cd2cc-745a-73ed-afa4-9adec29c9003" xlink:href="trs-20260331.xsd#trs_CashProceedsExpectedOnSettlementOfDerivative"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-70a8-8195-df0ce0b281e3" xlink:to="loc_trs_CashProceedsExpectedOnSettlementOfDerivative_019cd2cc-745a-73ed-afa4-9adec29c9003" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/SubsequentEventSaleofPropertyDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#SubsequentEventSaleofPropertyDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/SubsequentEventSaleofPropertyDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-71b1-96e7-0bb16907c438" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_019cd2cc-745a-70b3-a6ee-368484518b3c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-71b1-96e7-0bb16907c438" xlink:to="loc_us-gaap_SubsequentEventTable_019cd2cc-745a-70b3-a6ee-368484518b3c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019cd2cc-745a-736a-8203-5db25f2f7fa0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019cd2cc-745a-70b3-a6ee-368484518b3c" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019cd2cc-745a-736a-8203-5db25f2f7fa0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-736a-8203-5db25f2f7fa0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019cd2cc-745a-736a-8203-5db25f2f7fa0" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-736a-8203-5db25f2f7fa0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-7fec-a6a7-bf83c7e229c1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019cd2cc-745a-736a-8203-5db25f2f7fa0" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-7fec-a6a7-bf83c7e229c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019cd2cc-745a-74a9-87b1-63efb2f314ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-7fec-a6a7-bf83c7e229c1" xlink:to="loc_us-gaap_SubsequentEventMember_019cd2cc-745a-74a9-87b1-63efb2f314ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_019cd2cc-745a-7561-bbe1-1162da4c32e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-71b1-96e7-0bb16907c438" xlink:to="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_019cd2cc-745a-7561-bbe1-1162da4c32e8" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/SubsequentEventWeldmacDetails" xlink:type="simple" xlink:href="trs-20260331.xsd#SubsequentEventWeldmacDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/SubsequentEventWeldmacDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-71d0-b64d-62b0a687be45" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_019cd2cc-745a-7f08-8300-2d8ea1a88ff8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-71d0-b64d-62b0a687be45" xlink:to="loc_us-gaap_SubsequentEventTable_019cd2cc-745a-7f08-8300-2d8ea1a88ff8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019cd2cc-745a-7a96-9936-3e366d730e4e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019cd2cc-745a-7f08-8300-2d8ea1a88ff8" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019cd2cc-745a-7a96-9936-3e366d730e4e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-7a96-9936-3e366d730e4e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019cd2cc-745a-7a96-9936-3e366d730e4e" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-7a96-9936-3e366d730e4e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-7f77-b058-1134013b4a2d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019cd2cc-745a-7a96-9936-3e366d730e4e" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-7f77-b058-1134013b4a2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019cd2cc-745a-7925-b872-1f1791790c38" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019cd2cc-745a-7f77-b058-1134013b4a2d" xlink:to="loc_us-gaap_SubsequentEventMember_019cd2cc-745a-7925-b872-1f1791790c38" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019cd2cc-745a-782c-8ccc-dc0e81a9a0f5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019cd2cc-745a-7f08-8300-2d8ea1a88ff8" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019cd2cc-745a-782c-8ccc-dc0e81a9a0f5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd2cc-745a-782c-8ccc-dc0e81a9a0f5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019cd2cc-745a-782c-8ccc-dc0e81a9a0f5" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd2cc-745a-782c-8ccc-dc0e81a9a0f5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd2cc-745a-7893-8d9b-4b14f1dee6be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019cd2cc-745a-782c-8ccc-dc0e81a9a0f5" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd2cc-745a-7893-8d9b-4b14f1dee6be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_WeldmacManufacturingCompanyMember_019cd2cc-745a-7753-a87f-2c180125f2e8" xlink:href="trs-20260331.xsd#trs_WeldmacManufacturingCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd2cc-745a-7893-8d9b-4b14f1dee6be" xlink:to="loc_trs_WeldmacManufacturingCompanyMember_019cd2cc-745a-7753-a87f-2c180125f2e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventsDate_019cd2cc-745a-7381-b3e3-92eb9d501b01" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventsDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-71d0-b64d-62b0a687be45" xlink:to="loc_us-gaap_SubsequentEventsDate_019cd2cc-745a-7381-b3e3-92eb9d501b01" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019cd2cc-745a-7638-9d13-58aaf1d42d6d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019cd2cc-745a-71d0-b64d-62b0a687be45" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019cd2cc-745a-7638-9d13-58aaf1d42d6d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#IndividualsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2025/ecd-2025.xsd#ecd_AllIndividualsMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_HerbertK.ParkerMember_019dc0fd-b689-73aa-bb9c-b1b2a4dbba54" xlink:href="trs-20260331.xsd#trs_HerbertK.ParkerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_trs_HerbertK.ParkerMember_019dc0fd-b689-73aa-bb9c-b1b2a4dbba54" xlink:type="arc" order="2"/>
  </link:definitionLink>
</link:linkbase>
