WordNet (r) 3.0 (2006):

disgruntled
    adj 1: in a state of sulky dissatisfaction [syn: disgruntled,
           dissatisfied]

Moby Thesaurus II by Grady Ward, 1.0:

76 Moby Thesaurus words for "disgruntled":
   against, annoyed, bad-tempered, beefing, bellyaching, bitching,
   browned off, complaining, complaintful, con, crabbing, crabby,
   cranky, croaking, cross, disappointed, disapprobatory,
   disapproving, discontent, discontented, disenchanted,
   disillusioned, displeased, dissatisfied, dissenting, envious,
   exasperated, faultfinding, fed up, griping, grouchy, grousing,
   growling, grumbling, grumpy, ill-humored, ill-tempered, indignant,
   irritated, low, malcontent, malcontented, moody, murmuring,
   muttering, opposed, opposing, out of humor, peeved, peevish,
   petulant, poor, put out, querulant, querulous, rebellious,
   resentful, restive, restless, sulky, sullen, testy, turned-off,
   unaccepting, unaccommodating, unappreciative, unapproving,
   uncomplimentary, uneasy, unfavorable, unfulfilled, ungratified,
   unhappy, unsatisfied, vexed, whiny