propositus vs somebody

propositus and somebody both are nouns.

Word	Noun	Adjective	Verb	Adverb
propositus	Yes	No	No	No
somebody	Yes	No	No	No

As nouns, somebody is a hypernym of propositus; that is, somebody is a word with a broader meaning than propositus:

propositus: the person immediately affected by or concerned with an action
somebody: a human being; person, singular, assertive existential pronoun; pronoun, person, singular; quantifier: assertive existential

Other hypernyms of propositus include individual, mortal, person, someone, soul.

propositus (noun)	somebody (noun)
the person immediately affected by or concerned with an action	a human being; person, singular, assertive existential pronoun; pronoun, person, singular; quantifier: assertive existential