grumbling vs grumble

grumbling and grumble both are nouns.

Word	Noun	Adjective	Verb	Adverb
grumbling	Yes	Yes	No	No
grumble	Yes	No	Yes	No

As nouns, grumbling and grumble are synonyms defined as:

Other synonyms of grumbling include murmur, murmuring, mutter, muttering.

As nouns, grumbling and grumble are synonyms defined as:

Other synonyms of grumbling include rumble, rumbling.

grumbling (noun)	grumble (noun)
a complaint uttered in a low and indistinct tone	a complaint uttered in a low and indistinct tone
a loud low dull continuous noise	a loud low dull continuous noise

grumbling (adjective)	grumble (adjective)
continuous full and low-pitched throbbing sound

grumbling (verb)	grumble (verb)
	make complaining remarks or noises under one's breath
	show one's unhappiness or critical attitude
	to utter or emit low dull rumbling sounds
	make a low noise