step in verb 2step-in noun 1forms 4 verb2 •To get involved; to act.HM Chief Inspector of Railways has stepped in to speed up work to resolve incidents of overspeeding, having been concerned that progress on the issue has been too slow. — 2026 •To act as a replacement or substitute. step-in noun1 •An item of clothing which one steps into to put on; specifically, women's panties.‘Doc got that step-in in Memphis,’ the third said. ‘Off a damn whore.’ — 1931 formsstepped in · stepping in · steps in · step-ins