mutter vs gnarl

mutter and gnarl both are nouns.

Word	Noun	Adjective	Verb	Adverb
mutter	Yes	No	Yes	No
gnarl	Yes	No	Yes	No

As verbs, mutter and gnarl are synonyms defined as:

Other synonyms of mutter include croak, grumble, murmur.

mutter (noun)	gnarl (noun)
a complaint uttered in a low and indistinct tone	something twisted and tight and swollen
a low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech

mutter (verb)	gnarl (verb)
make complaining remarks or noises under one's breath	make complaining remarks or noises under one's breath
talk indistinctly; usually in a low voice	twist into a state of deformity