signior vs adult male

signior and adult male both are nouns.

Word	Noun	Adjective	Verb	Adverb
signior	Yes	No	No	No
adult male	Yes	No	No	No

As nouns, adult male is a hypernym of signior; that is, adult male is a word with a broader meaning than signior:

signior: used as an Italian courtesy title; can be prefixed to the name or used separately
adult male: an adult person who is male (as opposed to a woman)

Other hypernyms of signior include man.

signior (noun)	adult male (noun)
used as an Italian courtesy title; can be prefixed to the name or used separately	an adult person who is male (as opposed to a woman)