sound off vs kvetch

sound off is not a noun while kvetch is a noun.

Word	Noun	Adjective	Verb	Adverb
sound off	No	No	Yes	No
kvetch	Yes	No	Yes	No

As verbs, sound off and kvetch are synonyms defined as:

sound off and kvetch: express complaints, discontent, displeasure, or unhappiness

Other synonyms of sound off include complain, kick, plain, quetch.

sound off (noun)	kvetch (noun)
	(Yiddish) a nagging complaint
	(Yiddish) a constant complainer

sound off (verb)	kvetch (verb)
express complaints, discontent, displeasure, or unhappiness	express complaints, discontent, displeasure, or unhappiness
express one's opinion openly and without fear or hesitation
start playing