1. Of or relating to psychosis or psychoses, particularly behaviour associated with them. Psychotic behaviour occurs when a person is suffering psychoses, which may be the result of a chronic illness (classically schizophrenia) or very transient in which case it is usually caused by intoxicants. In any case, "psychotic" by definition means "of or relating to psychoses" therefore only behaviour that is due to a psychosis is truly "psychotic" by extension. A psychosis represents loss of contact with reality; it may or may not include delusional, paranoid or disorganised behaviour.
2. Informal and erroneous, though by far the most common lay usage. Refers to extreme behaviour that appears exaggerated, dangerously violent, or motivated by extreme rage. Is usually frightening to observers.
1. The young man entered a psychotic state and responded only to the same "Sigma," an entity he believed had gained remote control of his cortex during a recent abduction.
2. "Just saw the most intense road rage ever. This psychotic guy got out of his car with a club and started smashing the other dude's windows in"