Source : Webster's Revised Unabridged Dictionary (1913)

Derange \De*range"\, v. t. [imp. & p. p. {Deranged}; p. pr. &
   vb. n. {Deranging}.] [F. d['e]ranger; pref. d['e]- = d['e]s-
   (L. dis) + ranger to range. See {Range}, and cf.
   {Disarrange}, {Disrank}.]
   1. To put out of place, order, or rank; to disturb the proper
      arrangement or order of; to throw into disorder,
      confusion, or embarrassment; to disorder; to disarrange;
      as, to derange the plans of a commander, or the affairs of
      a nation.

   2. To disturb in action or function, as a part or organ, or
      the whole of a machine or organism.

            A sudden fall deranges some of our internal parts.
                                                  --Blair.

   3. To disturb in the orderly or normal action of the
      intellect; to render insane.

   Syn: To disorder; disarrange; displace; unsettle; disturb;
        confuse; discompose; ruffle; disconcert.

Source : WordNet®

derange
     v 1: derange mentally, throw out of mental balance; make insane;
          "The death of his parents unbalanced him" [syn: {unbalance}]
     2: throw into great confusion or disorder; "Fundamental
        Islamicists threaten to perturb the social order in
        Algeria and Egypt" [syn: {perturb}, {throw out of kilter}]