schoolmaster vs adult male

schoolmaster and adult male both are nouns.

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

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

Other hypernyms of schoolmaster include man, head, head teacher, principal, school principal.

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

Other hypernyms of schoolmaster include educator, pedagog, pedagogue, man.

schoolmaster (noun)	adult male (noun)
food fish of warm Caribbean and Atlantic waters	an adult person who is male (as opposed to a woman)
presiding officer of a school
any person (or institution) who acts as an educator