stern vs body part

stern and body part both are nouns.

Word	Noun	Adjective	Verb	Adverb
stern	Yes	Yes	No	No
body part	Yes	No	No	No

As nouns, body part is a hypernym of stern; that is, body part is a word with a broader meaning than stern:

stern (noun)	body part (noun)
the rear part of a ship	any part of an organism such as an organ or extremity
the fleshy part of the human body that you sit on

stern (adjective)	body part (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