unmarried woman vs woman

unmarried woman and woman both are nouns.

Word	Noun	Adjective	Verb	Adverb
unmarried woman	Yes	No	No	No
woman	Yes	No	No	No

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

Other hypernyms of unmarried woman include adult female.

unmarried woman (noun)	woman (noun)
a woman who is not married	women as a class
	an adult female person (as opposed to a man)
	a female person who plays a significant role (wife or mistress or girlfriend) in the life of a particular man