stark vs stern

stark is not a noun while stern is a noun.

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

As adjectives, stark and stern are synonyms defined as:

Other synonyms of stark include austere, severe.

stark (noun)	stern (noun)
	the rear part of a ship
	the fleshy part of the human body that you sit on

stark (adjective)	stern (adjective)
complete or extreme	severe and unremitting in making demands
providing no shelter or sustenance	not to be placated or appeased or moved by entreaty
severely simple	of a stern or strict bearing or demeanor; forbidding in aspect
devoid of any qualifications or disguise or adornment	severely simple
without qualification; used informally as (often pejorative) intensifiers

stark (adverb)	stern (adverb)
to the fullest degree