noun, plural psy·chos.

a psychopathic or psychotic person.
a crazy or mentally unstable person.


psychopathic or psychotic.
crazy; mentally unstable.

Origin of psycho

First recorded in 1935–40; by shortening


a combining form representing psyche (psychological) and psychological (psychoanalysis) in compound words.
Also especially before a vowel, psych-.

Origin of psycho-

< Greek, combining form of psȳchḗ breath, spirit, soul, mind; akin to psȳ́chein to blow (see psykter) Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for psycho

Contemporary Examples of psycho

Historical Examples of psycho

  • Down the hall, a patient screamed suddenly in the psycho ward.

    Criminal Negligence

    Jesse Francis McComas

  • It was so in keeping with his features that it served to strengthen the psycho diagnosis.

    The Old Martians

    Roger Phillips Graham

  • Hell, don't you know any language but that psycho double-talk?

    The Planet Savers

    Marion Zimmer Bradley

  • Psycho wouldn't do you any good if you weren't, that's the truth.

    Dangerous Ages

    Rose Macaulay

  • Maybe he was psycho and they didn't notice; they had some godawful asses for psychiatrists in war medicine.

    The Brain

    Alexander Blade

British Dictionary definitions for psycho


noun, adjective plural -chos

an informal and offensive word for psychopath or psychopathicSee psychopath


sometimes before a vowel psych-

combining form

indicating the mind or psychological or mental processespsychology; psychogenesis; psychosomatic

Word Origin for psycho-

from Greek psukhē spirit, breath
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 psycho

1927, shortening of psychological; 1936 (Raymond Chandler) as shortening of psychopathic (adj.).


1925, short for psychologist; as short for psychopath from 1942.


word-forming element meaning "mind, mental; spirit, unconscious," from Greek psykho-, combining form of psykhe (see psyche). It also was used to form compounds in Greek, e.g. psychopates "soul-beguiling."

Online Etymology Dictionary, © 2010 Douglas Harper

psycho in Medicine




A psychopath.


Crazy; insane.



Mind; mental:psychogenic.
Mental activities or processes:psychomotor.
Psychology; psychological:psychosocial.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.