kvetch vs mutter

kvetch and mutter both are nouns.

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

As verbs, mutter is a hyponym of kvetch; that is, mutter is a word with a more specific, narrower meaning than kvetch:

kvetch (noun)	mutter (noun)
(Yiddish) a nagging complaint	a complaint uttered in a low and indistinct tone
(Yiddish) a constant complainer	a low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech

kvetch (verb)	mutter (verb)
express complaints, discontent, displeasure, or unhappiness	make complaining remarks or noises under one's breath
	talk indistinctly; usually in a low voice