stern vs implacable

stern is a noun but implacable is not a noun.

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

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

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