- 1a state of extreme excitement, fear, or anger in which a person, or a group of people, loses control of their emotions and starts to cry, laugh, etc. There was mass hysteria when the band came on stage. A note of hysteria crept into her voice.
- 2(disapproving) an extremely excited and exaggerated way of behaving or reacting to an event the usual media hysteria that surrounds royal visits public hysteria about AIDS
- 3(medical) a condition in which someone experiences violent or extreme emotions that they cannot control, especially as a result of shock