The Collaborative International Dictionary of English v.0.48:

Tremble \Trem"ble\, n.
   An involuntary shaking or quivering.
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         I am all of a tremble when I think of it. --W. Black.
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The Collaborative International Dictionary of English v.0.48:

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.
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            I tremble still with fear.            --Shak.
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            Frighted Turnus trembled as he spoke. --Dryden.
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   2. To totter; to shake; -- said of a thing.
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            The Mount of Sinai, whose gray top
            Shall tremble.                        --Milton.
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   3. To quaver or shake, as sound; to be tremulous; as the
      voice trembles.
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WordNet (r) 3.0 (2006):

tremble
    n 1: a reflex motion caused by cold or fear or excitement [syn:
         tremble, shiver, shake]
    v 1: move or jerk quickly and involuntarily up and down or
         sideways; "His hands were trembling when he signed the
         document"