In Greek:
Hystera = womb or uterus
Hysterikos = a suffering in the womb

Plato and his followers described the uterus as an animal endowed with spontaneous sensation and motion, lodged in a woman, and ardently desiring to bear children. If it remained sterile long after puberty, it became indignant, dissatisfied, and ill-tempered and caused a general disturbance of the body until it became pregnant, when it became normal again.
This is in keeping with the age-old proclivity to attribute various abnormal manifestations to specific organs of the body. Emotional instability, thought to be more characteristic of women than men, was atttributed to the uterus." [1]
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1. William S. Haubrich. Medical Meanings - a glossary of word origins. American College of Physicians Philadelphia Pennsylvania 1997: p 107