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

Lead plaintiff Matthew McAfee capitalized on the generous odds and won $150,000. —Michael McCann, Sportico.com, 16 Dec. 2025

Moving that revenue out from under CBP’s purview will make clawing it back for refunds a significant challenge in the event that the Supreme Court rules against the administration, the corporate plaintiffs believe. —Kate Nishimura, Sourcing Journal, 16 Dec. 2025

The lawsuit listed California, 15 other states and the District of Columbia as plaintiffs. —Chaewon Chung december 16, Sacbee.com, 16 Dec. 2025

Lizzo is addressing the latter of those accusations now that the plaintiffs have rescinded that aspect of their complaint. —Marci Robin, Allure, 15 Dec. 2025

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