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]

Moby Thesaurus II by Grady Ward, 1.0:

64 Moby Thesaurus words for "sarcasm":
   Atticism, acerbity, acridity, acridness, acrimony, agile wit,
   asperity, bitterness, black humor, burlesque, caricature,
   causticity, comedy, contumely, corrosiveness, cynicism, derision,
   disdain, dry wit, esprit, farce, gibe, harshness, humor, innuendo,
   invective, irony, jest, lampoon, malevolence, malice,
   maliciousness, mockery, nimble wit, parody, pleasantry, poison,
   poisonousness, pretty wit, quick wit, raillery, rancor, ready wit,
   repartee, ridicule, salt, satire, satiric wit, savor of wit, scorn,
   sharpness, slapstick, slapstick humor, sneering, spite,
   spitefulness, squib, subtle wit, travesty, venom, venomousness,
   virulence, visual humor, wit