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

• 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

Bryan Pease, who represented the plaintiffs with his partner Parisa Ijadi-Maghsoodi, said the city’s priorities have been misplaced. —Kelly Davis, San Diego Union-Tribune, 30 Sep. 2025

The remainder is earmarked for other plaintiffs in the case, including the American Conservative Union, Andrew Baggiani, Austen Fletcher, Maryse Veronica Jean-Louis, Frank Valentine, Kelly Victory and Naomi Wolf. —Winston Cho, HollywoodReporter, 29 Sep. 2025

Mark Zuckerberg’s Meta agreed early this year to pay $25 million to settle, with about $22 million going to Trump’s presidential library and the rest to legal fees and other plaintiffs. —Jill Goldsmith, Deadline, 29 Sep. 2025

The plaintiffs in each case -- the ACLU and Washington State attorney general -- provided ABC News with copies of the government's filings. —Devin Dwyer, ABC News, 28 Sep. 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