mass hysteria vs epidemic hysertia

mass hysteria and epidemic hysertia both are nouns.

Word	Noun	Adjective	Verb	Adverb
mass hysteria	Yes	No	No	No
epidemic hysertia	Yes	No	No	No

As nouns, mass hysteria and epidemic hysertia are synonyms defined as:

mass hysteria and epidemic hysertia: a condition in which a large group of people exhibit the same state of violent mental agitation

mass hysteria (noun)	epidemic hysertia (noun)
a condition in which a large group of people exhibit the same state of violent mental agitation	a condition in which a large group of people exhibit the same state of violent mental agitation