missy vs ring girl

missy and ring girl both are nouns.

Word	Noun	Adjective	Verb	Adverb
missy	Yes	No	No	No
ring girl	Yes	No	No	No

As nouns, ring girl is a hyponym of missy; that is, ring girl is a word with a more specific, narrower meaning than missy:

missy: a young female
ring girl: a young woman who holds up cards indicating the number of the next round at prize fights

missy (noun)	ring girl (noun)
a young female	a young woman who holds up cards indicating the number of the next round at prize fights