The Collaborative International Dictionary of English v.0.48:

condescending \condescending\ adj.
   exhibiting an attitude of superiority; patronizing; -- used
   of behavior or attitude.

   Syn: arch, patronizing.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Condescend \Con`de*scend"\, v. i. [imp. & p. p. Condescended;
   p. pr. & vb. n. Condescending.] [F. condescendre, LL.
   condescendere, fr. L. con- + descendere. See Descend.]
   1. To stoop or descend; to let one's self down; to submit; to
      waive the privilege of rank or dignity; to accommodate
      one's self to an inferior. "Condescend to men of low
      estate." --Rom. xii. 16.
      [1913 Webster]

            Can they think me so broken, so debased
            With corporal servitude, that my mind ever
            Will condescend to such absurd commands? --Milton.
      [1913 Webster]

            Spain's mighty monarch,
            In gracious clemency, does condescend,
            On these conditions, to become your friend.
                                                  --Dryden.
      [1913 Webster]

   Note: Often used ironically, implying an assumption of
         superiority.
         [1913 Webster]

               Those who thought they were honoring me by
               condescending to address a few words to me. --F.
                                                  W. Robinson.
         [1913 Webster]

   2. To consent. [Obs.]
      [1913 Webster]

            All parties willingly condescended heruento. --R.
                                                  Carew.

   Syn: To yield; stoop; descend; deign; vouchsafe.
        [1913 Webster] Condescendence

WordNet (r) 3.0 (2006):

condescending
    adj 1: (used of behavior or attitude) characteristic of those
           who treat others with condescension [syn: arch,
           condescending, patronizing, patronising]

Moby Thesaurus II by Grady Ward, 1.0:

34 Moby Thesaurus words for "condescending":
   arrogant, belittling, big, contemptuous, disdainful, domineering,
   haughty, high-faluting, high-flown, high-handed, high-hat,
   high-headed, high-nosed, hoity-toity, imperious, lofty,
   overbearing, patronizing, pompous, priggish, proud, purse-proud,
   sniffy, snippy, snobbish, snobby, snooty, snotty, stuck-up,
   superior, toplofty, uppish, uppity, upstage