The New Dictionary of Cultural Literacy, Third Edition. 2002.
psychosis
(seye-KOH-sis) A severe mental disorder, more serious than neurosis, characterized by disorganized thought processes, disorientation in time and space, hallucinations, and delusions. Paranoia, manic depression, megalomania, and schizophrenia are all psychoses. One who suffers from psychosis is psychotic.