yack away vs yack

yack away is not a noun while yack is a noun.

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

As verbs, yack away and yack are synonyms defined as:

Other synonyms of yack away include jaw, rattle on, yap away.

yack away (noun)	yack (noun)
	noisy talk

yack away (verb)	yack (verb)
talk incessantly and tiresomely	talk incessantly and tiresomely