unappeasable vs stern

unappeasable is not a noun while stern is a noun.

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

As adjectives, unappeasable and stern are synonyms defined as:

unappeasable and stern: not to be placated or appeased or moved by entreaty

Other synonyms of unappeasable include grim, inexorable, relentless, unforgiving, unrelenting.

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

unappeasable (adjective)	stern (adjective)
not to be placated or appeased or moved by entreaty	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