WordNet (r) 3.0 (2006):

good luck
    n 1: an auspicious state resulting from favorable outcomes [syn:
         good fortune, luckiness, good luck] [ant: bad luck,
         ill luck, misfortune, tough luck]
    2: a stroke of luck [syn: good luck, fluke, good fortune]
    3: an unexpected piece of good luck; "he finally got his big
       break" [syn: break, good luck, happy chance]

Moby Thesaurus II by Grady Ward, 1.0:

45 Moby Thesaurus words for "good luck":
   accidentality, actuarial calculation, adventitiousness, blessing,
   break, casualness, chance, destiny, fate, felicity, flukiness,
   fortuitousness, fortuity, fortunateness, fortune, gamble,
   good fortune, hap, happenstance, happy chance, happy fortune,
   heedless hap, how they fall, indeterminacy, indeterminateness,
   law of averages, lot, luck, luckiness, moira, opportunity,
   principle of indeterminacy, probability, problematicness,
   random sample, risk, run of luck, serendipity, smiles of fortune,
   statistical probability, the breaks, theory of probability,
   uncertainty, uncertainty principle, whatever comes