Dictionary

A person who is psychotic or otherwise insane.

Example: The loony bin up on the hill is full of psychos.

A person who acts in a bizarre or dangerous manner.

Example: She complained that he was a psycho for driving at such a high speed in heavy traffic.

Psychotic, or otherwise insane.

A class, at a college or university, in which psychology is taught.

Example: I've got anthro, socio, lunch, and psycho.