Synonyms for Grumble:

n.

complaint, whine, rant, protest, remonstrance, fuss. lodge, snap, bark, roar, kick up a fuss/stink/argument, raise the roof, snarl, take something further, splutter. resound, pulsate, resonate, purr. groan, thud, pitch, happy, clunk. boom. sounds. communication (noun)
murmur, muttering, mutter, murmuring, grumbling.
complaint (noun)
remonstrance.
event (noun)
rumble, grumbling, rumbling.
grumble (noun)
muttering, gnarl, grumbling, murmuring, rumbling, croak, murmur, grouch, rumble, growl, scold, mutter.
rumble (noun)
drone, drum, racket, hum, chant, clatter, throb, rumble, rattle, beat, chatter, roll, buzz, thrum, reverberation, thunder.

v.

gripe (verb)
murmur.
grumble (verb)
grouch, growl, protest, mutter, fuss, groan, snarl, snap, roar, bark, gnarl, scold, croak, splutter, roll, whine.
rumble (verb)
reverberate.

Other synonyms:

remonstrance, clunk, resound. rant, thud, snarl, resonate, pulsate. protest, boom, purr. groan. lodge. pitch. rumble
rumble.
sing
whine.
Other relevant words:
grouch, grumbling, resound, murmur, complaint, murmuring, muttering, snarl, scold, roar, whine, groan, protest, bark, mutter, thud, rumbling, growl, fuss, snap, splutter, gnarl, boom, croak.

Usage examples for grumble

  1. But owing to the scarcity of business that now came my way, Theodore had little or nothing to do, and he was in very truth eating his head off, and with that, grumble grumble all the time, threatening to leave me, if you please, to leave my service for more remunerative occupation. – Castles in the Air by Baroness Emmuska Orczy
  2. As long as you can fix me up with what I want for my work I shan't grumble about the rest. – A Rogue by Compulsion by Victor Bridges
  3. They had done what was best under the circumstances; still the boys felt rather inclined to grumble about it one winter morning when they were starting off to the village on an errand. – Our Young Folks at Home and Abroad by Various