action

Action refers to the process of doing something that produces a change or result. The term derives from Latin actio, act- “to do.” It is used across many disciplines to denote both a specific deed and the chain of events that follows it.

In everyday language, an action is a deliberate act by a person or an agent, such as making a decision, speaking, or moving an object, as well as events that occur as a consequence of such acts.

In philosophy and social theory, action theory investigates what distinguishes intentional actions from mere bodily movements, emphasizing agency, reasons, beliefs, and desires that guide behavior.

In physics, action is a quantity defined as the integral over time of the Lagrangian function; the principle of least action says the true motion makes this integral stationary, leading to the laws of motion.

In legal contexts, an action can mean a lawsuit or legal proceeding; civil actions address disputes between private parties, while criminal actions involve government prosecution.

In linguistics, action is commonly described by verbs that express events or dynamic processes; in film and literature, action as a genre emphasizes physical activity and forward momentum.