grumble

noun

1
make complaining remarks or noises under one's breath
she grumbles when she feels overworked
2
show one's unhappiness or critical attitude
He scolded about anything that he thought was wrong
We grumbled about the increased work load
3
to utter or emit low dull rumbling sounds
he grumbled a rude response
Stones grumbled down the cliff
4
make a low noise
rumbling thunder

Also useful for “grumble”:Unscrambler— Rearrange the letters in “grumble”