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

The driver denied touching the plaintiff, Uber said. —CBS News, 21 Apr. 2026

Also, in their filing, plaintiffs are asking a judge to rule that ‘third-party brand sponsors’ are not associated with the school, so their deals with players would not need to be approved by the College Sports Commission. —Trey Wallace Outkick, FOXNews.com, 21 Apr. 2026

The plaintiffs, Le Soleil Child Care LLC, and three parents who send or planned to send their students to the French immersion day care, declined an interview through their lawyers. —Idaho Statesman, 21 Apr. 2026

In February, the city banded with more than a dozen other cities and counties to become additional plaintiffs in an existing lawsuit filed last summer by a group led by Fresno, California. —Mirtha Donastorg, AJC.com, 21 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