Which term refers to a legal proceeding initiated by a plaintiff against a defendant?

The term that best describes a legal proceeding initiated by a plaintiff against a defendant is litigation. Litigation encompasses the process of going to court to resolve disputes and is characterized by the formal legal actions taken to enforce or defend one's rights. This often involves the filing of complaints, discovery, and trial proceedings where a judge or jury decides the outcome based on the evidence presented.

In contrast, arbitration and mediation are forms of alternative dispute resolution that allow parties to resolve their disputes outside the courtroom. Arbitration involves a neutral third party making a binding decision, while mediation focuses on facilitating communication between parties to help them reach a mutually agreeable solution. Negotiation refers to discussions aimed at reaching an agreement but does not necessarily involve formal legal actions or the court system. Thus, litigation stands out as the term specifically pertaining to the court process initiated by a plaintiff against a defendant.