An energumen (from Greek 'energoumenos', possessed) is a frantic and hysterical person, who commonly shows a strength superior to what he/she should have. Sometimes this term applies to some maniacs. An energumen is also a demon-possessed person (obsolete). Hysteria is a state of mind, one of unmanageable fear or emotional excesses. ... In psychiatry a maniac is a person who suffers the mental disease called mania. ... Demonic possession is a form of spiritual possession; specifically, the act of one or more demons entering a living or dead human or animal body or an object with the intention of using it for a purpose, normally evil but sometimes instead as a punishment or test. ...