unstable vs crank

unstable is not a noun while crank is a noun.

Word	Noun	Adjective	Verb	Adverb
unstable	No	Yes	No	No
crank	Yes	Yes	Yes	No

unstable (noun)	crank (noun)
	a hand tool consisting of a rotating shaft with parallel handle
	an amphetamine derivative (trade name Methedrine) used in the form of a crystalline hydrochloride; used as a stimulant to the nervous system and as an appetite suppressant
	a bad-tempered person
	a whimsically eccentric person

unstable (adjective)	crank (adjective)
lacking stability or fixity or firmness	(used of boats) inclined to heel over easily under sail
subject to change; variable
suffering from severe mental illness
disposed to psychological variability
highly or violently reactive
affording no ease or reassurance