The Collaborative International Dictionary of English v.0.48:

Unhinge \Un*hinge"\, v. t. [1st pref. un- + hinge.]
   [1913 Webster]
   1. To take from the hinges; as, to unhinge a door.
      [1913 Webster]

   2. To displace; to unfix by violence. --Blackmore.
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   3. To render unstable or wavering; to unsettle; as, to
      unhinge one's mind or opinions; to unhinge the nerves.
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            Why should I then unhinge my brains, ruin my mind?
                                                  --South.
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            His sufferings, nay the revolutions of his fate, had
            not in the least unhinged his mind.   --Walpole.
      [1913 Webster]

WordNet (r) 3.0 (2006):

unhinge
    v 1: disturb in mind or make uneasy or cause to be worried or
         alarmed; "She was rather perturbed by the news that her
         father was seriously ill" [syn: perturb, unhinge,
         disquiet, trouble, cark, distract, disorder]
    2: remove the hinges from; "unhinge the door"