grumble vs growl

grumble and growl both are nouns.

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

As verbs, grumble and growl are synonyms defined as:

Other synonyms of grumble include rumble.

grumble (noun)	growl (noun)
a complaint uttered in a low and indistinct tone	the sound of growling (as made by animals)
a loud low dull continuous noise

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