possibility vs impossible

possibility and impossible both are nouns.

Word	Noun	Adjective	Verb	Adverb
possibility	Yes	No	No	No
impossible	Yes	Yes	No	No

possibility (noun)	impossible (noun)
a tentative insight into the natural world; a concept that is not yet verified but that if true would explain certain facts or phenomena	something that cannot be done
a possible alternative
a future prospect or potential
capability of existing or happening or being true

possibility (adjective)	impossible (adjective)
	not capable of occurring or being accomplished or dealt with
	(used of persons or their behavior) not acceptable or reasonable
	totally unlikely