hit the books vs bone

hit the books is not a noun while bone is a noun.

Word	Noun	Adjective	Verb	Adverb
hit the books	No	No	Yes	No
bone	Yes	Yes	Yes	No

As verbs, bone is a hyponym of hit the books; that is, bone is a word with a more specific, narrower meaning than hit the books:

Other hyponyms of hit the books include con, learn, memorise, memorize, bone up, cram, drum, get up, grind away, mug up, swot, swot up.

hit the books (noun)	bone (noun)
	a shade of white the color of bleached bones
	rigid connective tissue that makes up the skeleton of vertebrates
	the porous calcified substance from which bones are made

hit the books (adjective)	bone (adjective)
	consisting of or made up of bone

hit the books (verb)	bone (verb)
learn by reading books	remove the bones from
	study intensively, as before an exam