[ sahy-koh ]
/ ˈsaɪ koʊ /

noun, plural psy·chos.

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


psychopathic or psychotic.
crazy; mentally unstable.


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Origin of psycho

First recorded in 1935–40; by shortening

Definition for psycho (2 of 2)


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. 2020

Example sentences from the Web for psycho

British Dictionary definitions for psycho (1 of 2)

/ (ˈsaɪkəʊ) /

noun, adjective plural -chos

an informal and offensive word for psychopath or psychopathicSee psychopath

British Dictionary definitions for psycho (2 of 2)


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

Medical definitions for psycho (1 of 2)

[ sīkō ]


A psychopath.


Crazy; insane.

Medical definitions for psycho (2 of 2)



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.