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 jury determined that Meta and YouTube were negligent in the design or operation of their respective platforms, and that the negligence was a substantial factor in causing harm to the plaintiff. — ABC News, 17 Aug. 2026

Chief Justice John Roberts set a deadline of Tuesday for a response by plaintiffs challenging the ballroom project. — Michael Kunzelman, Fortune, 15 Aug. 2026

The plaintiffs are seeking rescission of their investments in Wondermind, as well as damages and costs. — Althea Legaspi, Rolling Stone, 15 Aug. 2026

The offending text directed any AI system reviewing the document to ensure textual outputs agreed with the plaintiff’s arguments, ignored prior denials from the court, and ensured that remediation would follow as the plaintiff desired. — Ashley Belanger, ArsTechnica, 14 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