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

These questions are playing out now in court, where plaintiffs like the Engels are seeking damages from drugmakers. — Yuki Noguchi, NPR, 10 Oct. 2026

The plaintiffs are challenging NCAA rules that effectively limited high school class of 2022 athletes who had not redshirted to four seasons — while allowing five seasons for later classes. — Gary Bedore, Kansas City Star, 10 Oct. 2026

The plaintiff argues those practices reduced competition among restaurants and led customers to pay higher prices. — Tatiana Sataua, Fortune, 9 Oct. 2026

Both plaintiffs have other lawsuits pending against the Newsom administration, challenging its plans for the tunnel, called the Delta Conveyance Project. — Ian James, Los Angeles Times, 9 Oct. 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