Source : Webster's Revised Unabridged Dictionary (1913)

Tremble \Trem"ble\, v. i. [imp. & p. p. {Trembled}; p. pr. & vb.
   n. {Trembling}.] [F. trembler, fr. L. tremulus trembling,
   tremulous, fr. tremere to shake, tremble; akin to Gr. ?,
   Lith. trimti. Cf. {Tremulous}, {Tremor}.]
   1. To shake involuntarily, as with fear, cold, or weakness;
      to quake; to quiver; to shiver; to shudder; -- said of a
      person or an animal.

            I tremble still with fear.            --Shak.

            Frighted Turnus trembled as he spoke. --Dryden.

   2. To totter; to shake; -- said of a thing.

            The Mount of Sinai, whose gray top Shall tremble.
                                                  --Milton.

   3. To quaver or shake, as sound; to be tremulous; as the
      voice trembles.

Tremble \Trem"ble\, n.
   An involuntary shaking or quivering.

         I am all of a tremble when I think of it. --W. Black.

Source : WordNet®

tremble
     n : reflex shaking caused by cold or fear or excitement [syn: {shiver},
          {shake}]

tremble
     v : move or jerk quickly and involuntarily up and down or
         sideways; "His hands were trembling when he signed the
         document"