widow woman vs adult female

widow woman and adult female both are nouns.

Word	Noun	Adjective	Verb	Adverb
widow woman	Yes	No	No	No
adult female	Yes	No	No	No

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

widow woman: a woman whose husband is dead especially one who has not remarried
adult female: an adult female person (as opposed to a man)

Other hypernyms of widow woman include woman.

widow woman (noun)	adult female (noun)
a woman whose husband is dead especially one who has not remarried	an adult female person (as opposed to a man)