Schizophrenia: a long-term mental disorder of a type involving a breakdown in the relation between thought, emotion, and behaviour, leading to faulty perception, inappropriate actions and feelings, withdrawal from reality and personal relationships into fantasy and delusion, and a sense of mental fragmentation. Claustrophobia: extreme or irrational fear of confined places. Kleptomania: a recurrent urge to steal, typically without regard for need or profit. Megalomania: obsession with the exercise of power.