Synonyms of grumbler

1 Syllable
crab, bear, crank, bug, grouch, grump
2 Syllables
grouser, sulkers, gripers, grouches, crabbing, sourpuss, kicker, grouched, growler, crosspatch, moaner, whiner, griper, sulker
3 Syllables
sniveler, malcontent, curmudgeon, snivelers, complainer, complainers, mutterers, murmurer, crybaby, mutterer, faultfinder, bellyacher, sorehead