yack away vs jaw

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

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

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

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

yack away (noun)	jaw (noun)
	holding device consisting of one or both of the opposing parts of a tool that close to hold an object
	the part of the skull of a vertebrate that frames the mouth and holds the teeth
	the bones of the skull that frame the mouth and serve to open it; the bones that hold the teeth

yack away (verb)	jaw (verb)
talk incessantly and tiresomely	talk socially without exchanging too much information
	censure severely or angrily
	talk incessantly and tiresomely
	chew (food); to bite and grind with the teeth