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 allege Bio-Lab and the parent company, Kik LLC, had a history of chemical storage issues, and staff incorrectly tried to put out a water-reactive chemical reaction by adding water before the fire began, thereby causing the fire and toxic gas plume. — Irene Wright, USA Today, 23 June 2026

Using the algorithm, station owners inflated gasoline by as much as 22 cents a gallon and diesel by 33 cents, on top of already high prices caused by the US war with Iran, the plaintiffs alleged. — Bloomberg, Mercury News, 23 June 2026

After medical expenses are deducted, the woman would receive about $178,400 if the settlement is approved, according to the plaintiffs’ attorneys’ court papers. — City News Service, Daily News, 23 June 2026

While most of the plaintiffs were Christians, that is not true in all of them. — Los Angeles Times, 23 June 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