The Collaborative International Dictionary of English v.0.48:

Witty \Wit"ty\, a. [Compar. Wittier; superl. Wittiest.] [AS.
   witig, wittig. See Wit, n.]
   [1913 Webster]
   1. Possessed of wit; knowing; wise; skillful; judicious;
      clever; cunning. [Obs.] "The deep-revolving witty
      Buckingham." --Shak.
      [1913 Webster]

   2. Especially, possessing wit or humor; good at repartee;
      droll; facetious; sometimes, sarcastic; as, a witty
      remark, poem, and the like. "Honeycomb, who was so
      unmercifully witty upon the women." --Addison.
      [1913 Webster]

   Syn: Acute; smart; sharp; arch; keen; facetious; amusing;
        humorous; satirical; ironical; taunting.
        [1913 Webster] Witwal

WordNet (r) 3.0 (2006):

witty
    adj 1: combining clever conception and facetious expression;
           "his sermons were unpredictably witty and satirical as
           well as eloquent"

Moby Thesaurus II by Grady Ward, 1.0:

51 Moby Thesaurus words for "witty":
   Attic, absurd, amusing, biting, bizarre, brilliant, clever,
   diverting, droll, eccentric, entertaining, facetious, funny,
   hilarious, humorous, humorsome, incongruous, jesting, jocose,
   jocular, joking, joky, joshing, keen, keen-witted, laughable,
   ludicrous, mordant, nimble-witted, penetrating, piercing, pointed,
   priceless, probing, pungent, quaint, quick-witted, quizzical,
   rapier-like, rich, ridiculous, risible, salt, salty, scintillating,
   screaming, sharp, smart, sparkling, sprightly, whimsical