Cupid's itch vs contagion

Cupid's itch and contagion both are nouns.

Word	Noun	Adjective	Verb	Adverb
Cupid's itch	Yes	No	No	No
contagion	Yes	No	No	No

As nouns, contagion is a hypernym of Cupid's itch; that is, contagion is a word with a broader meaning than Cupid's itch:

Cupid's itch: a communicable infection transmitted by sexual intercourse or genital contact
contagion: any disease easily transmitted by contact

Other hypernyms of Cupid's itch include contagious disease.

Cupid's itch (noun)	contagion (noun)
a communicable infection transmitted by sexual intercourse or genital contact	the communication of an attitude or emotional state among a number of people
	an incident in which an infectious disease is transmitted
	any disease easily transmitted by contact