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

Jason Henry | Bloomberg | Getty Images The Meta settlement came just over a week into a federal trial in Oakland, California, that was co-led on the plaintiff side by California AG Rob Bonta. — Jonathan Vanian, CNBC, 30 Aug. 2026

Before the settlement, the plaintiffs had made a strong case. — Benjamin Wallace-Wells, New Yorker, 30 Aug. 2026

The smartest plaintiffs' attorneys are doing a good job shopping for judges sympathetic to their cases — and there are more than 30 at the moment with nearly 400 athletes involved. — ABC News, 30 Aug. 2026

There won’t be group of plaintiffs next year like the ones this year because there’s no group that will have been limited to four years. — Michael McCann, Sportico.com, 29 Aug. 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