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 in Wednesday's lawsuit argued the order unconstitutionally intrudes on Congress and the states' power to regulate elections, since the Constitution doesn't give the president any direct authority over how federal elections are conducted. —Jacob Rosen, CBS News, 2 Apr. 2026

The Board of Estimates approved $230,271 for five different injury claims against the city, though $455,271 total in settlements were recommended to be paid to plaintiffs by the city’s legal department. —Chevall Pryce, Baltimore Sun, 2 Apr. 2026

So for example, there's no mechanism for Barbara, the woman who's the lead plaintiff in this suit. —Dana Taylor, USA Today, 2 Apr. 2026

Attorney Ben Crane represented the plaintiffs in the 2015 case and also represented the pedestrian’s estate in the wrongful death lawsuit. —Talia Soglin, Chicago Tribune, 2 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