groom vs adult male

groom and adult male both are nouns.

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

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

Other hypernyms of groom include man, honeymooner, newlywed.

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

Other hypernyms of groom include man, participant, player.

groom (noun)	adult male (noun)
a man who has recently been married	an adult person who is male (as opposed to a woman)
someone employed in a stable to take care of the horses
a man participant in his own marriage ceremony

groom (verb)	adult male (verb)
care for one's external appearance
give a neat appearance to
educate for a future role or function