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 judges said the plaintiffs should have mounted their legal challenge within four years from the time the statistical methods were used. —Arkansas Online, 5 Feb. 2026

The plaintiff is seeking payment including compensation for medical costs, lost wages and suffering. —Bay Area News Group, Mercury News, 5 Feb. 2026

The plaintiffs argued that the surge was not genuinely aimed at curbing immigration violations, but was designed instead to coerce the cities and the state into participating in federal immigration enforcement, a violation of the 10th Amendment. —Los Angeles Times, 5 Feb. 2026

In her 83-page ruling, Reyes said the Haitian plaintiffs were likely to succeed on the merits of their claims. —Jacqueline Charles, Miami Herald, 5 Feb. 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