What is the legal term for a complaint initiated by a plaintiff?

The legal term for a complaint initiated by a plaintiff is best described as a lawsuit. A lawsuit refers to the formal legal action taken by a plaintiff seeking a legal remedy from a defendant, typically involving a claim that the defendant has committed a wrongful act or has failed to perform a legal duty.

In the context of the legal system, when a plaintiff files a lawsuit, they are formally bringing their case before a court, which may involve various documents including the complaint itself that outlines the legal reasons why the defendant should be held liable. This process includes the initiation of legal proceedings and can lead to various outcomes, including a trial or settlement.

While a claim refers more broadly to the assertion of a right or legal entitlement and is often part of the content of a lawsuit, the term "petition" typically involves a request made to the court, often used in specific types of cases such as family law or bankruptcy. A motion is a request made to the court for a specific ruling or order, rather than the overarching action of commencing a legal case. Thus, identifying the correct term as a lawsuit encapsulates the entire process of the legal complaint initiated by the plaintiff.