IPA: //ˈswɪm.suːt//
KK: /ˈswɪmˌsʊt/
A piece of clothing designed to be worn for swimming or sunbathing.
She bought a new swimsuit for her vacation at the beach.
Swimsuit is formed from "swim" (from Old English "swimman", meaning to move through water) and "suit" (from Old French "suite", meaning a set of clothing). The word "swimsuit" refers to a set of clothing designed for swimming or water activities.
Think of moving through water ('swim') while wearing a set of clothing ('suit') — that's what a swimsuit is for.
No commonly confused words.