rumble vs grumble

rumble and grumble both are nouns.

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

As nouns, rumble and grumble are synonyms defined as:

Other synonyms of rumble include grumbling, rumbling.

As verbs, rumble and grumble are synonyms defined as:

Other synonyms of rumble include growl.

As verbs, rumble and grumble are synonyms defined as:

rumble (noun)	grumble (noun)
a fight between rival gangs of adolescents	a complaint uttered in a low and indistinct tone
a servant's seat (or luggage compartment) in the rear of a carriage	a loud low dull continuous noise
a loud low dull continuous noise

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