posteriority vs posterior

posteriority and posterior both are nouns.

Word	Noun	Adjective	Verb	Adverb
posteriority	Yes	No	No	No
posterior	Yes	Yes	No	No

posteriority (noun)	posterior (noun)
the quality of being toward the back or toward the rear end	the fleshy part of the human body that you sit on
following in time	a tooth situated at the back of the mouth

posteriority (adjective)	posterior (adjective)
	located at or near or behind a part or near the end of a structure
	coming at a subsequent time or stage