Dr. Zahiruddin Othman discusses concepts and definitions related to psychosis. Psychosis has been conceptualized in various ways throughout history such as shamanism, demonic possession, lunacy, and witchcraft. Definitions of psychosis focus on symptoms such as delusions and hallucinations. Psychotic symptoms include hallucinations, delusions, disorganized speech, and disorganized or catatonic behavior. Schizophrenia, schizophreniform disorder, brief psychotic disorder, and other psychiatric disorders can involve psychotic symptoms.