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]

Moby Thesaurus II by Grady Ward, 1.0:

116 Moby Thesaurus words for "disapprove":
   abjure, attaint, ban, belittle, bespatter, blackball, blacken,
   blame, blot, blow upon, brand, brush aside, categorically reject,
   censure, chuck, chuck out, condemn, contemn, contradict, criticize,
   decline, decry, defame, defile, denounce, deny, deplore, deprecate,
   depreciate, despise, detract, disallow, disapprove of, discard,
   disclaim, discommend, discount, discountenance, disdain, disesteem,
   disfavor, dismiss, disown, disparage, dispraise, disregard,
   dissent from, except, exclude, expose, expose to infamy,
   expostulate, forswear, frown, frown at, frown down, frown upon,
   gibbet, grimace at, hang in effigy, ignore, knock, look askance at,
   look black upon, not approve, not go for, not hear of,
   not hold with, object, object to, oppose, ostracize, pass by,
   pass up, pillory, protest, push aside, put down, rebuff, recant,
   refuse, refuse to consider, reject, remonstrate, renounce, repel,
   reprehend, reprimand, reprobate, repudiate, repulse, run down,
   say no to, scout, shove away, slur, smear, soil, spurn, stain,
   stigmatize, sully, taint, take exception to, tarnish, think ill of,
   think little of, throw away, throw out, thumb down, turn away,
   turn down, turn out, view with disfavor, vilify, waive