"female organ of gestation, womb," late 14c., from Latin uterus "womb, belly" (plural uteri), from PIE root *udero- "abdomen, womb, stomach" (source also of Sanskrit udaram "belly," Greek hystera "womb," Lithuanian vėderas "sausage, intestines, stomach, lower abdomen," Old Church Slavonic vedro "bucket, barrel," Russian vedro).
word-forming element in names of countries, diseases, and flowers, from Latin and Greek -ia, noun ending, in Greek especially used in forming abstract nouns (typically of feminine gender); see -a (1). The classical suffix in its usual evolution (via French -ie) comes to Modern English as -y (as in familia/family, also -logy, -graphy). Compare -cy.
In paraphernalia, Mammalia, regalia, etc. it represents Latin or Greek -a (see -a (2)), plural suffix of nouns in -ium (Latin) or -ion (Greek), with formative or euphonic -i-.
1610s, "characteristic of hysteria," the nervous disease originally defined as a neurotic condition peculiar to women and thought to be caused by a dysfunction of the uterus; literally "of the womb," from Latin hystericus "of the womb," from Greek hysterikos "of the womb, suffering in the womb," from hystera "womb," from PIE *udtero-, variant of *udero- "abdomen, womb, stomach" (see uterus). Compare hysteria.
Meaning "very funny" (by 1939) is from the notion of uncontrollable fits of laughter. For "inclined to hysteria," American English formerly had the colloquial hystericky (1792). Related: Hysterically.