• Unusual, maladaptive, uncomfortable and bizarre behaviour

  • DSM: “Clinically significant behaviour, associated with distress and disability, not simply a predictable and culturally sanctioned response to a particular event, which is considered to reflext behavioural, psychological or biological dysfunction”

  • Wakefield: - mental condition that causes significant distress and disability which is not merely an acceptable response to a particular event and is a manifestation of mental dysfunction.

  • Abnormality