Definition - What does Plaintiff mean?
A plaintiff is a person or entity that sues another person or entity by bringing a case against them in a court of law. The term plaintiff finds its origin in the Anglo-French word "pleintif" which means complaining.
Justipedia explains Plaintiff
In the United States legal system, anyone who accuses another person or entity of a wrongdoing or sues them is addressed as "plaintiff" except in administrative law and extrajudicial process in insurance where the term "claimant" is used. The party, against whom the plaintiff files the case, is known as the defendant. In litigation, the plaintiff makes allegations of wrongdoing against the defendant. If the court finds merit in the allegations levied by the plaintiff, it issues a judgment in favor of the plaintiff. In a class action lawsuit, the plaintiff identified by his or her name is known as a named plaintiff.
In some family law courts the term "plaintiff" is replaced with the word "petitioner."