The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

         The sarcasms of those critics who imagine our art to be
         a matter of inspiration.                 --Sir J.
                                                  Reynolds.
   [1913 Webster]

   Syn: Satire; irony; ridicule; taunt; gibe.
        [1913 Webster]

WordNet (r) 3.0 (2006):

sarcasm
    n 1: witty language used to convey insults or scorn; "he used
         sarcasm to upset his opponent"; "irony is wasted on the
         stupid"; "Satire is a sort of glass, wherein beholders do
         generally discover everybody's face but their own"--
         Jonathan Swift [syn: sarcasm, irony, satire, caustic
         remark]