Source : Webster's Revised Unabridged Dictionary (1913)

Expiration \Ex`pi*ra"tion\, n. [L. expiratio,exspiratio: cf. F.
   expiration. See {Expire}.]
   1. The act of expiring; as:
      (a) (Physiol.) The act or process of breathing out, or
          forcing air from the lungs through the nose or mouth;
          as, respiration consists of inspiration and
          expiration; -- opposed to {inspiration}.
      (b) Emission of volatile matter; exhalation.

                The true cause of cold is an expiration from the
                globe of the earth.               --Bacon.
      (c) The last emission of breath; death. ``The groan of
          expiration.'' --Rambler.
      (d) A coming to a close; cessation; extinction;
          termination; end.

                Before the expiration of thy time. --Shak.

   2. That which is expired; matter breathed forth; that which
      is produced by breathing out, as a sound.

            The aspirate ``he,'' which is . . . a gentle
            expiration.                           --G. Sharp.

Source : WordNet®

expiration
     n 1: a coming to an end of a contract period; "the expiry of his
          driver's license" [syn: {termination}, {expiry}]
     2: euphemistic expressions for death; "thousands mourned his
        passing" [syn: {passing}, {loss}, {departure}, {exit}, {going},
         {release}]
     3: the act of expelling air from the lungs [syn: {exhalation},
        {breathing out}]