kvetch vs sound off

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

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

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

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

Other synonyms of kvetch include complain, kick, plain, quetch.

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

kvetch (verb)	sound off (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