Definition of agent

The word "agent" has a rich history dating back to ancient Rome. The Latin term "agnos," meaning "cause" or "reason," is the root of the word. In Latin, an "agens" referred to a person who put a thing in motion or was the cause of an action. Over time, the term evolved to mean "doer" or "performer," and was used in Middle English (circa 1100-1500) to describe a person who acted on behalf of another. This sense of "agent" as a representative or intermediary remained in English-speaking cultures. Today, the term "agent" encompasses various meanings, including a person who acts on behalf of another (e.g., real estate agent, literary agent), a substance that produces a chemical reaction (e.g., catalyst), or even a software program that interacts with a user (e.g., user agent). Despite its varied uses, the word's roots remain in the Latin concept of "agnos," emphasizing the idea of causality and action.