grumblest

Verb

grumble (third-person singular simple present grumbles, present participle grumbling, simple past and past participle grumbled)

1. (intransitive) To make a low, growling or rumbling noise, like a hungry stomach or certain animals.
   • The distant thunder grumbles.
2. (intransitive) 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.
3. (transitive) To utter in a grumbling fashion.
   • He grumbled that there was no grain "in the country" and that people were talking instead of working to provide it.2001, Harry Willcox Pfanz, Gettysburg — the first day

See all 6 meanings of grumble