The Collaborative International Dictionary of English v.0.48:

Disapprove \Dis`ap*prove\, v. t. [imp. & p. p. Disapproved; p.
   pr. & vb. n. Disapproving.] [Pref. dis- + approve: cf. F.
   d['e]approuver. Cf. Disapprobation.]
   1. To pass unfavorable judgment upon; to condemn by an act of
      the judgment; to regard as wrong, unsuitable, or
      inexpedient; to censure; as, to disapprove the conduct of
      others.
      [1913 Webster]

   2. To refuse official approbation to; to disallow; to decline
      to sanction; as, the sentence of the court-martial was
      disapproved by the commander in chief.
      [1913 Webster]

   Note: This verb is often followed by of; as, to disapprove of
         an opinion, of such conduct. See Approve.
         [1913 Webster]

WordNet (r) 3.0 (2006):

disapprove
    v 1: consider bad or wrong [ant: approve]
    2: deem wrong or inappropriate; "I disapprove of her child
       rearing methods" [syn: disapprove, reject] [ant: O.K.,
       approve, okay, sanction]