posterior vs stern

posterior and stern both are nouns.

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

As nouns, posterior and stern are synonyms defined as:

posterior (noun)	stern (noun)
the fleshy part of the human body that you sit on	the rear part of a ship
a tooth situated at the back of the mouth	the fleshy part of the human body that you sit on

posterior (adjective)	stern (adjective)
located at or near or behind a part or near the end of a structure	severe and unremitting in making demands
coming at a subsequent time or stage	not to be placated or appeased or moved by entreaty
	of a stern or strict bearing or demeanor; forbidding in aspect
	severely simple