Source : Webster's Revised Unabridged Dictionary (1913)

Dismount \Dis*mount"\, v. i. [imp. & p. p. {Dismounted}; p. pr.
   & vb. n. {Dismounting}.] [Pref. dis- + mount: cf. OF.
   desmonter, F. d['e]monter.]
   1. To come down; to descend. [Poetic]

            But now the bright sun ginneth to dismount.
                                                  --Spenser.

   2. To alight from a horse; to descend or get off, as a rider
      from his beast; as, the troops dismounted.

Dismount \Dis*mount"\, v. t.
   1. To throw or bring down from an elevation, place of honor
      and authority, or the like.

            Dismounted from his authority.        --Barrow.

   2. To throw or remove from a horse; to unhorse; as, the
      soldier dismounted his adversary.

   3. (Mech.) To take down, or apart, as a machine.

   4. To throw or remove from the carriage, or from that on
      which a thing is mounted; to break the carriage or wheels
      of, and render useless; to deprive of equipments or
      mountings; -- said esp. of artillery.

Source : WordNet®

dismount
     n : the act of dismounting (a horse or bike etc.)
     v : get off (a horse) [syn: {unhorse}, {light}, {get off}, {get
         down}]