swain vs adult male

swain and adult male both are nouns.

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

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

Other hypernyms of swain include lover, man.

swain (noun)	adult male (noun)
a man who is the lover of a man or woman	an adult person who is male (as opposed to a woman)