The Collaborative International Dictionary of English v.0.48:

grouchy \grouch"y\ (grouch"[y^]), adj.
   given to complaining or grumbling; prone to show annoyance at
   slight provocation; irritable.

   Syn: crabbed, crabby, cross, fussy, fussbudgety, grumpy,
        bad-tempered, ill-tempered.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

grouchy
    adj 1: annoyed and irritable [syn: crabbed, crabby, cross,
           fussy, grouchy, grumpy, bad-tempered, ill-
           tempered]

Moby Thesaurus II by Grady Ward, 1.0:

46 Moby Thesaurus words for "grouchy":
   beefing, bellyaching, bitching, complaining, complaintful,
   crabbing, crabby, cranky, croaking, disappointed, discontented,
   disgruntled, displeased, dissatisfied, envious, faultfinding,
   griping, grousing, growling, gruff, grumbling, grumbly, grumpish,
   grumpy, malcontent, malcontented, murmuring, muttering,
   out of humor, peevish, petulant, querulant, querulous, rebellious,
   resentful, restive, restless, sulky, unaccepting, unaccommodating,
   uneasy, unfulfilled, ungratified, unhappy, unsatisfied, whiny