kvetch vs croak

kvetch and croak both are nouns.

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

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

kvetch (noun)	croak (noun)
(Yiddish) a nagging complaint	a harsh hoarse utterance (as of a frog)
(Yiddish) a constant complainer

kvetch (verb)	croak (verb)
express complaints, discontent, displeasure, or unhappiness	pass from physical life and lose all bodily attributes and functions necessary to sustain life
	make complaining remarks or noises under one's breath
	utter a hoarse sound, like a raven