Source : Webster's Revised Unabridged Dictionary (1913)

Mechanism \Mech"an*ism\, n. [Cf. F. m['e]canisme, L. mechanisma.
   See {Mechanic}.]
   1. The arrangement or relation of the parts of a machine; the
      parts of a machine, taken collectively; the arrangement or
      relation of the parts of anything as adapted to produce an
      effect; as, the mechanism of a watch; the mechanism of a
      sewing machine; the mechanism of a seed pod.

   2. Mechanical operation or action.

            He acknowledges nothing besides matter and motion;
            so that all must be performed either by mechanism or
            accident.                             --Bentley.

   3. (Kinematics) An ideal machine; a combination of movable
      bodies constituting a machine, but considered only with
      regard to relative movements.

Source : WordNet®

mechanism
     n 1: the atomic process that occurs during a chemical reaction;
          "he determined unique mechanisms for the photochemical
          reactions" [syn: {chemical mechanism}]
     2: the technical aspects of doing something; "a mechanism of
        social control"; "mechanisms of communication"; "the
        mechanics of prose style" [syn: {mechanics}]
     3: a natural object resembling a machine in structure or
        function; "the mechanism of the ear"; "the mechanism of
        infection"
     4: (philosophy) the philosophical theory that all phenomena can
        be explained in terms of physical or biological causes
     5: device consisting of a piece of machinery; has moving parts
        that perform some function