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 plaintiffs argued that oil and gas companies failed to warn consumers that their products (allegedly) contributed to climate change, thus ultimately causing damages. —Candy Campbell, Baltimore Sun, 16 Apr. 2026

The jury ruled unanimously in favor of the plaintiffs, a coalition of 33 states and the District of Columbia, which argued that Live Nation’s monopolized the market for ticketing and used its muscle to force artists to play its venues. —Gene Maddaus, Variety, 16 Apr. 2026

The judge’s ruling gives an advantage to plaintiffs to proceed that often encourages settlement negotiations. —Robert McCoppin, Chicago Tribune, 16 Apr. 2026

Each of the plaintiffs in this new suit, excluding Colin Albert, are the targets of Read’s own lawsuit first filed in Bristol County and then transferred to federal court in Boston. —Flint McColgan, Boston Herald, 16 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