Plaintiff/ˈpleɪntɪf/ Definition 1 of 1Pro Tip 1/3Initiates Action The plaintiff is the starter of the lawsuit, not the defender. When John filed his complaint, he became the plaintiff. Pro Tip 2/3Legal Context Use 'plaintiff' when referring to civil legal cases, not criminal ones. In the civil dispute, the plaintiff sought damages for breach of contract. Pro Tip 3/3Not Always Right Being the plaintiff doesn’t guarantee being correct or winning the case. The plaintiff's argument was weak, and he lost the case.