fellow vs adult male

fellow and adult male both are nouns.

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

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

Other hypernyms of fellow include lover, man.

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

Other hypernyms of fellow include man.

fellow (noun)	adult male (noun)
a boy or man	an adult person who is male (as opposed to a woman)
a man who is the lover of a man or woman
a friend who is frequently in the company of another
a person who is member of one's class or profession
an informal form of address for a man
a member of a learned society
one of a pair