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

With an attorney on the plaintiffs’ side of the lawsuit colluding with the city’s team, the city could settle the claims on favorable terms. —Dakota Smith, Los Angeles Times, 19 Feb. 2026

The plaintiff, Rigoberto Soto Jimenez, was arrested in mid-January, part of a monthslong immigration crackdown in Minnesota. —Jacob Rosen, CBS News, 19 Feb. 2026

Trial began Tuesday, and the plaintiff rested its breach-of-contract case just before the lunch break Wednesday. —Alexa Shrake, Dallas Morning News, 19 Feb. 2026

The plaintiffs were seeking a declaratory judgment that the tax exemptions granted to Amazon Data Services be declared null and void and that the resolutions passed by the Hobart City Council be declared null and void. —Deborah Laverty, Chicago Tribune, 19 Feb. 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