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

One plaintiff, Kyle Frankovich, had never heard of Johnson before the podcaster and online influencer posted video of Frankovich and a row of other protesters detained outside an ICE facility in Broadview, Ill. — Lisa Hagen, NPR, 2 Oct. 2026

Students for Fair Admissions was the plaintiff in the 2023 Supreme Court affirmative action cases. — Jaweed Kaleem, Los Angeles Times, 2 Oct. 2026

The mass settlement would resolve 16 lawsuits brought by 17 plaintiffs, all represented by the law firm Loevy & Loevy. — Jake Sheridan, Chicago Tribune, 1 Oct. 2026

The communications were released after the judge, in a rare move last month, granted the plaintiff’s request for the city to turn over any communications about the board’s decision. — Josephine Stratman, New York Daily News, 1 Oct. 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