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):

condescend
    v 1: behave in a patronizing and condescending manner
    2: do something that one considers to be below one's dignity
       [syn: condescend, deign, descend]
    3: debase oneself morally, act in an undignified, unworthy, or
       dishonorable way; "I won't stoop to reading other people's
       mail" [syn: condescend, stoop, lower oneself]
    4: treat condescendingly [syn: patronize, patronise,
       condescend]

Moby Thesaurus II by Grady Ward, 1.0:

42 Moby Thesaurus words for "condescend":
   OK, accede to, accept, accord to, agree to, approve, approve of,
   assent, be willing, bridle, connive at, consent,
   consent to silently, deal with, deign, descend, endorse,
   give consent, go along with, grant, have no objection, hold with,
   lower oneself, nod, nod assent, not refuse, okay, patronize,
   permit, ratify, sanction, say aye, say yes, stoop, take kindly to,
   toss the head, treat, vote affirmatively, vote aye, vouchsafe,
   wink at, yield assent