signorina vs unmarried woman

signorina and unmarried woman both are nouns.

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

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

signorina: an Italian courtesy title for an unmarried woman; equivalent to `Miss', it is either used alone or before a name
unmarried woman: a woman who is not married

signorina (noun)	unmarried woman (noun)
an Italian courtesy title for an unmarried woman; equivalent to `Miss', it is either used alone or before a name	a woman who is not married