Pronunciation: (hi-ster'ē-u, -stēr'-),[key] —n. 1. an uncontrollable outburst of emotion or fear, often characterized by irrationality, laughter, weeping, etc.
2. Psychoanal.a psychoneurotic disorder characterized by violent emotional outbreaks, disturbances of sensory and motor functions, and various abnormal effects due to autosuggestion.
3. Psychiatry.See conversion disorder. Cf. mass hysteria.