yack vs utter

yack is a noun but utter is not a noun.

Word	Noun	Adjective	Verb	Adverb
yack	Yes	No	Yes	No
utter	No	Yes	Yes	No

As verbs, utter is a hypernym of yack; that is, utter is a word with a broader meaning than yack:

Other hypernyms of yack include mouth, speak, talk, verbalise, verbalize.

yack (noun)	utter (noun)
noisy talk

yack (adjective)	utter (adjective)
	complete and absolute
	without qualification; used informally as (often pejorative) intensifiers

yack (verb)	utter (verb)
talk incessantly and tiresomely	express in speech
	articulate; either verbally or with a cry, shout, or noise
	express audibly; utter sounds (not necessarily words)
	put into circulation