ass vs stern

ass and stern both are nouns.

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

As nouns, ass and stern are synonyms defined as:

ass (noun)	stern (noun)
slang for sexual intercourse	the rear part of a ship
hardy and sure-footed animal smaller and with longer ears than the horse	the fleshy part of the human body that you sit on
the fleshy part of the human body that you sit on
a pompous fool

ass (adjective)	stern (adjective)
	severe and unremitting in making demands
	not to be placated or appeased or moved by entreaty
	of a stern or strict bearing or demeanor; forbidding in aspect
	severely simple