From Webster's Revised Unabridged Dictionary (1913) :

  Sarcasm \Sar"casm\, n. [F. sarcasme, L. sarcasmus, Gr.
     sarkasmo`s, from sarka`zein to tear flesh like dogs, to bite
     the lips in rage, to speak bitterly, to sneer, fr. sa`rx,
     sa`rkos, flesh.]
     A keen, reproachful expression; a satirical remark uttered
     with some degree of scorn or contempt; a taunt; a gibe; a
     cutting jest.
  
           The sarcasms of those critics who imagine our art to be
           a matter of inspiration.                 --Sir J.
                                                    Reynolds.
  
     Syn: Satire; irony; ridicule; taunt; gibe.

From WordNet (r) 1.6 :

  sarcasm
       n : witty language used to convey insults or scorn; "he used
           sarcasm to upset his opponent"; "irony is wasted on the
           stupid" [syn: irony, satire, caustic remark]
 
-Dustin (who, as several people have pointed out, is a different person from NightStorm... but a nice shot, Jon)