Source : Webster's Revised Unabridged Dictionary (1913)

Action \Ac"tion\, n. [OF. action, L. actio, fr. agere to do. See
   {Act}.]
   1. 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.

            One wise in council, one in action brave. --Pope.

   2. An act; a thing done; a deed; an enterprise. (pl.):
      Habitual deeds; hence, conduct; behavior; demeanor.

            The Lord is a Good of knowledge, and by him actions
            are weighed.                          --1 Sam. ii.
                                                  3.

   3. 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.

   4. Movement; as, the horse has a spirited action.

   5. (Mech.) Effective motion; also, mechanism; as, the breech
      action of a gun.

   6. (Physiol.) 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.

   7. (Orat.) Gesticulation; the external deportment of the
      speaker, or the suiting of his attitude, voice, gestures,
      and countenance, to the subject, or to the feelings.

   8. (Paint. & Sculp.) The attitude or position of the several
      parts of the body as expressive of the sentiment or
      passion depicted.

   9. (Law)
      (a) A suit or process, by which a demand is made of a
          right in a court of justice; in a broad sense, a
          judicial proceeding for the enforcement or protection
          of a right, the redress or prevention of a wrong, or
          the punishment of a public offense.
      (b) A right of action; as, the law gives an action for
          every claim.

   10. (Com.) A share in the capital stock of a joint-stock
       company, or in the public funds; hence, in the plural,
       equivalent to stocks. [A Gallicism] [Obs.]

             The Euripus of funds and actions.    --Burke.

   11. An engagement between troops in war, whether on land or
       water; a battle; a fight; as, a general action, a partial
       action.

   12. (Music) The mechanical contrivance by means of which the
       impulse of the player's finger is transmitted to the
       strings of a pianoforte or to the valve of an organ pipe.
       --Grove.

   {Chose in action}. (Law) See {Chose}.

   {Quantity of action} (Physics), the product of the mass of a
      body by the space it runs through, and its velocity.

   Syn: {Action}, {Act}.

   Usage: In many cases action and act are synonymous; but some
          distinction is observable. Action involves the mode or
          process of acting, and is usually viewed as occupying
          some time in doing. Act has more reference to the
          effect, or the operation as complete.

                To poke the fire is an act, to reconcile friends
                who have quarreled is a praiseworthy action.
                                                  --C. J. Smith.

Source : WordNet®

action
     n 1: something done (usually as opposed to something said);
          "there were stories of murders and other unnatural
          actions"
     2: the state of being active; "his sphere of activity"; "he is
        out of action" [syn: {activity}, {activeness}] [ant: {inaction},
         {inaction}, {inaction}]
     3: a judicial proceeding brought by one party against another;
        one party prosecutes another for a wrong done or for
        protection of a right or for prevention of a wrong [syn: {legal
        action}, {action at law}]
     4: an act by a government body or supranational organization;
        "recent federal action undermined the segregationist
        position"; "the United Nations must have the power to
        propose and organize action without being hobbled by
        irrelevant issues"; "the Union action of emancipating
        Southern slaves"
     5: a military engagement; "he saw action in Korea" [syn: {military
        action}]
     6: a process existing in or produced by nature (rather than by
        the intent of human beings); "the action of natural
        forces"; "volcanic activity" [syn: {natural process}, {natural
        action}, {activity}]
     7: the series of events that form a plot; "his novels always
        have a lot of action"
     8: the operating part that transmits power to a mechanism; "the
        piano had a very stiff action" [syn: {action mechanism}]
     9: the trait of being active and energetic and forceful; "a man
        of action"
     10: the most important or interesting work or activity in a
         specific area or field; "the action is no longer in
         technology stocks but in municipal bonds"; "gawkers
         always try to get as close to the action as possible"

action
     v 1: institute legal proceedings against; file a suit against;
          "He was warned that the district attorney would process
          him"; "She actioned the company for discrimination"
          [syn: {sue}, {litigate}, {process}]
     2: put in effect; "carry out a task"; "execute the decision of
        the people"; "He actioned the operation" [syn: {carry
        through}, {accomplish}, {execute}, {carry out}, {fulfill},
         {fulfil}]