stern vs sternness

stern and sternness both are nouns.

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

stern (noun)	sternness (noun)
the rear part of a ship	uncompromising resolution
the fleshy part of the human body that you sit on	the quality (as of scenery) being grim and gloomy and forbidding

stern (adjective)	sternness (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