geezer vs adult male

geezer and adult male both are nouns.

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

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

Other hypernyms of geezer include man.

geezer (noun)	adult male (noun)
a man who is (usually) old and/or eccentric	an adult person who is male (as opposed to a woman)