Definition

• n. - A process or condition of acting or moving, as opposed to rest; the doing of something; exertion of power or force, as when one body acts on another; the effect of power exerted on one body by another; agency; activity; operation; as, the action of heat; a man of action.
• n. - An act; a thing done; a deed; an enterprise. (pl.): Habitual deeds; hence, conduct; behavior; demeanor.
• n. - The event or connected series of events, either real or imaginary, forming the subject of a play, poem, or other composition; the unfolding of the drama of events.
• n. - Movement; as, the horse has a spirited action.
• n. - Effective motion; also, mechanism; as, the breech action of a gun.
• n. - Any one of the active processes going on in an organism; the performance of a function; as, the action of the heart, the muscles, or the gastric juice.