noun, plural psy·cho·ses [-seez] /-siz/. Psychiatry.

a mental disorder characterized by symptoms, such as delusions or hallucinations, that indicate impaired contact with reality.
any severe form of mental disorder, as schizophrenia or paranoia.

Origin of psychosis

First recorded in 1840–50, psychosis is from the Late Greek word psȳ́chōsis animation, principle of life. See psych-, -osis Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for psychosis

Contemporary Examples of psychosis

Historical Examples of psychosis

  • In some exceptional cases a genuine neurosis or psychosis may develop.


    William J. Robinson

  • If you have a psychosis, you behave in response to delusions or hallucinations.

  • She was seventy-eight this year, clouded by senility along with the psychosis.

  • Then, at the engagement dinner of the brother, the psychosis broke out.

    Benign Stupors

    August Hoch

  • There is, further, the history of a delusion of death during the onset of the psychosis.

    Benign Stupors

    August Hoch

British Dictionary definitions for psychosis


noun plural -choses (-ˈkəʊsiːz)

any form of severe mental disorder in which the individual's contact with reality becomes highly distortedCompare neurosis

Word Origin for psychosis

C19: New Latin, from psycho- + -osis
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for psychosis

1847, "mental derangement," Modern Latin, from Greek psykhe- "mind" (see psyche) + -osis "abnormal condition." Greek psykhosis meant "a giving of life; animation; principle of life."

Online Etymology Dictionary, © 2010 Douglas Harper

psychosis in Medicine



n. pl. psy•cho•ses (-sēz)

A severe mental disorder, with or without organic damage, characterized by derangement of personality and loss of contact with reality and causing deterioration of normal social functioning.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

psychosis in Science



Plural psychoses (sī-kōsēz)

A mental state caused by psychiatric or organic illness, characterized by a loss of contact with reality and an inability to think rationally. A psychotic person often behaves inappropriately and is incapable of normal social functioning.
Related formspsychotic adjective (sī-kŏtĭk)
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

psychosis in Culture



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.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.