unfit vs impaired

unfit and impaired both are adjectives.

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

unfit (adjective)	impaired (adjective)
not in good physical or mental condition; out of condition	diminished in strength, quality, or utility
below the required standards for a purpose	mentally or physically unfit
physically unsound or diseased

unfit (verb)	impaired (verb)
make unfit or unsuitable