The Collaborative International Dictionary of English v.0.48:

Fiasco \Fi*as"co\, n.; pl. Fiascoes. [It.]
   A complete or ridiculous failure, esp. of a musical
   performance, or of any pretentious undertaking.
   [1913 Webster]

WordNet (r) 3.0 (2006):

fiasco
    n 1: a sudden and violent collapse [syn: debacle, fiasco]

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "fiasco":
   abortion, bafflement, balk, betrayed hope, blasted expectation,
   blighted hope, blow, bollix, botch, buffet, bungle, comedown,
   cruel disappointment, dash, dashed hope, defeat, disappointment,
   disaster, discomfiture, disillusionment, dissatisfaction, failure,
   fallen countenance, fizzle, flop, flunk, foiling, foozle,
   forlorn hope, frustration, hash, hope deferred, letdown, mess,
   mirage, muddle, setback, sore disappointment, tantalization, tease,
   washout