The Collaborative International Dictionary of English v.0.48:

grouch \grouch\ (grouch), n.
   A bad-tempered person.

   Syn: grump, crank, churl, crosspatch.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

grouch \grouch\ v. i.
   to complain habitually, especially about minor or routine
   annoyances.

   Syn: grumble, gripe.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

grouch
    n 1: a bad-tempered person [syn: grouch, grump, crank,
         churl, crosspatch]
    v 1: show one's unhappiness or critical attitude; "He scolded
         about anything that he thought was wrong"; "We grumbled
         about the increased work load" [syn: grouch, grumble,
         scold]

Moby Thesaurus II by Grady Ward, 1.0:

70 Moby Thesaurus words for "grouch":
   Tartar, air a grievance, bear, beef, bellyache, bellyacher, bitch,
   clamor, complain, complainant, complainer, crab, crank, croak,
   croaker, crosspatch, dragon, faultfinder, feist, fire-eater, fret,
   fret and fume, frondeur, fury, fuss, gripe, griper, grizzly bear,
   groan, grouse, grouser, growl, growler, grumble, grumbler, grump,
   grunt, holler, hothead, hotspur, howl, kick, kicker, killjoy,
   kvetch, lodge a complaint, malcontent, mope, murmur, murmurer,
   mutter, mutterer, querulous person, raise a howl, reactionary,
   reactionist, rebel, register a complaint, scold, sorehead,
   sourpuss, spoilsport, squawk, sulk, take on, ugly customer,
   wet blanket, whiner, yap, yelp