hysterics (n.)

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.

in the names of sciences or disciplines (acoustics, aerobics, economics, etc.), a 16c. revival of the classical custom of using the neuter plural of adjectives with Greek -ikos "pertaining to" (see -ic) to mean "matters relevant to" and also as the titles of treatises about them. Subject matters that acquired their English names before c. 1500, however, tend to be singular in form (arithmetic, logic, magic, music, rhetoric). The grammatical number of words in -ics (mathematics is/mathematics are) is a confused question.