jaw vs brush down

jaw is a noun but brush down is not a noun.

Word	Noun	Adjective	Verb	Adverb
jaw	Yes	No	Yes	No
brush down	No	No	Yes	No

As verbs, brush down is a hyponym of jaw; that is, brush down is a word with a more specific, narrower meaning than jaw:

Other hyponyms of jaw include castigate, chasten, chastise, correct, objurgate, tell off.

jaw (noun)	brush down (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

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