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 are asking that the clinic inform all patients who stored their embryos with the clinic before the plaintiff's implantation, WESH reported, citing court documents. —Madison E. Goldberg, PEOPLE, 22 Jan. 2026

The lawsuit was dismissed without prejudice, meaning the plaintiffs can refile their lawsuit in the future if federal agents again violate their First Amendment Rights. —Sara Tenenbaum, CBS News, 22 Jan. 2026

One plaintiff had a tooth knocked loose when an officer struck her in the head with a baton. —Los Angeles Times, 22 Jan. 2026

The plaintiffs had been customers of the bank for decades, the suit says. —Dan Mangan,hugh Son, CNBC, 22 Jan. 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