grumbler vs grumble

grumbler and grumble both are nouns.

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

grumbler (noun)	grumble (noun)
a person given to excessive complaints and crying and whining	a complaint uttered in a low and indistinct tone
	a loud low dull continuous noise

grumbler (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