Irishwoman vs adult female

Irishwoman and adult female both are nouns.

Word	Noun	Adjective	Verb	Adverb
Irishwoman	Yes	No	No	No
adult female	Yes	No	No	No

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

Other hypernyms of Irishwoman include Irelander, Irish person, woman.

Irishwoman (noun)	adult female (noun)
a woman who is a native or inhabitant of Ireland	an adult female person (as opposed to a man)