unfit vs crookback

unfit is not a noun while crookback is a noun.

Word	Noun	Adjective	Verb	Adverb
unfit	No	Yes	Yes	No
crookback	Yes	Yes	No	No

unfit (noun)	crookback (noun)
	a person whose back is hunched because of abnormal curvature of the upper spine

unfit (adjective)	crookback (adjective)
not in good physical or mental condition; out of condition	characteristic of or suffering from kyphosis, an abnormality of the vertebral column
below the required standards for a purpose
physically unsound or diseased

unfit (verb)	crookback (verb)
make unfit or unsuitable