nullipara vs adult female

nullipara and adult female both are nouns.

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

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

Other hypernyms of nullipara include woman.

nullipara (noun)	adult female (noun)
(obstetrics) a woman who has never give birth to a child	an adult female person (as opposed to a man)