plaintiff

noun

plain·​tiff ˈplān-təf 

: a person who brings a legal action compare defendant

Did you know?

We won't complain about the origins of plaintiff, although complain and plaintiff are distantly related; both can be traced back to plangere, a Latin word meaning "to strike, beat one's breast, or lament." Plaintiff comes most immediately from Middle English plaintif, itself an Anglo-French borrowing tracing back to plaint, meaning "lamentation." (The English word plaintive is also related.) Logically enough, plaintiff applies to the one who does the complaining in a legal case.

Synonyms of plaintiff

• complainant
• accuser
• appellant

Examples of plaintiff in a Sentence

the judge ruled that the plaintiff's lawsuit was groundless, and he dismissed it

Recent Examples on the Web

Since plaintiffs were foreclosed, by Section 230, from arguing that social-media companies are liable for publishing harmful content, lawyers came up with a claim that attempted to sidestep it. —Jeannie Suk Gersen, New Yorker, 9 Apr. 2026

Kelly was one of the plaintiffs in the case, which made it to the 3rd District Court of Appeal. —Stephen Hobbs, Sacbee.com, 9 Apr. 2026

Along with Dreyer, Silver Golub & Teitell partner Sarah Russell represented the plaintiffs at trial, the firm noted. —Staff Report, Hartford Courant, 9 Apr. 2026

That suit was settled in the plaintiff’s favor last year when Bambaataa didn’t show up for court. —Brian Niemietz, New York Daily News, 9 Apr. 2026

Word History

Etymology

Middle English plaintif, from Anglo-French, from pleintif, adjective

First Known Use

14th century, in the meaning defined above

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Kids Definition

plaintiff

noun

plain·​tiff ˈplānt-əf 

: the complaining party in a lawsuit

Legal Definition

plaintiff

noun

plain·​tiff ˈplān-təf 

: the party who institutes a legal action or claim (as a counterclaim) see also complainant, complaint, libellant compare defendant, prosecution

Etymology

Middle French plaintif, from plaintif, adj., grieving, from plaint lamentation, from Latin planctus, from plangere to strike, beat one's breast, lament