IPA: //ˈlɔː.suːt//
KK: /ˈlɔːˌsuːt/
A legal action taken by one person or group against another in a court of law to resolve a dispute or seek compensation.
She filed a lawsuit against the company for unfair dismissal.
Lawsuit is formed from "law" (from Old English *lagu*, meaning a rule or regulation) and "suit" (from Old French *suit*, meaning a following or pursuit). The term refers to a legal action where one party pursues a claim against another under the law.
Think of 'law' as the rules we follow and 'suit' as the act of pursuing something — a lawsuit is when someone follows the rules to pursue a legal claim.
No commonly confused words.