GRUMBLING

To make a low, growling or rumbling noise, like a hungry stomach or certain animals.

"The distant thunder grumbles."

To complain; to murmur or mutter with discontent; to make ill-natured complaints in a low voice and a surly manner.

"He grumbles about the food constantly, but has yet to learn to cook."

To utter in a grumbling fashion.

Complaining

"the grumblings of a bad-tempered man"

Rumbling