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

That same year, millions of plaintiffs filed an antitrust class action lawsuit seeking over $1 billion in damages that alleged Sutter Health overcharged customers and companies for health care bills and discouraged clients from using other lower-cost services. —Kyle Martin, Mercury News, 13 Oct. 2025

The limited public profile of the plaintiffs highlights how modern constitutional test cases are often organized by lawyers or advocacy groups seeking a particular ruling. —Robert Alexander, MSNBC Newsweek, 13 Oct. 2025

The federal courts in 2022 sided with the plaintiffs’ claim that the plan did violate the Voting Rights Act and ordered the state legislature to redraw the congressional plan with a second Black-majority district. —Sam D. Hayes, The Conversation, 13 Oct. 2025

One of the anonymous plaintiffs called out Ellison for supporting the policies that have allowed the trans pitcher to play against females. —Jackson Thompson, FOXNews.com, 11 Oct. 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