improbable vs probable

improbable is not a noun while probable is a noun.

Word	Noun	Adjective	Verb	Adverb
improbable	No	Yes	No	No
probable	Yes	Yes	No	No

improbable (noun)	probable (noun)
	an applicant likely to be chosen

improbable (adjective)	probable (adjective)
not likely to be true or to occur or to have occurred	likely but not certain to be or become true or real
having a probability too low to inspire belief	apparently destined
too improbable to admit of belief