psycho

¹ American  

[sahy-koh] / ˈsaɪ koʊ /

noun

plural

psychos

1. a psychopathic or psychotic person.

2. a crazy or mentally unstable person.

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adjective

1. psychopathic or psychotic.

2. crazy; mentally unstable.

psycho- ² American  

1. a combining form representing psyche (psychological ) and psychological (psychoanalysis ) in compound words.

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psycho- ¹ British  

combining form

1. indicating the mind or psychological or mental processes

   psychology

   psychogenesis

   psychosomatic

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psycho ² British  

/ ˈsaɪkəʊ /

noun

1. an informal and offensive word for psychopath or psychopathic See psychopath

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Usage

What does psycho- mean? Psycho- is a combining form used like a prefix meaning either “psyche” or "psychological." Psyche denotes "the human soul, spirit, or mind," while psychological is a related yet distinct term that means "pertaining to psychology, the science of the mind or of mental states." Psycho- is often used in medical and technical terms, especially in psychology.Psycho- comes from Greek psȳchḗ, meaning “breath, spirit, soul, mind.” For more on the meaning of this word in Ancient Greek mythology, read our entry for psyche. The word psyche is at the root of the term psychedelic, which refers to the effect of hallucinogenic drugs.What are variants of psycho-?When combined with words or word elements that begin with a vowel, psycho- becomes psych-, as in psychiatry. Want to know more? Read our Words That Use article on psych-.

Etymology

Origin of psycho¹

First recorded in 1935–40; by shortening

Origin of psycho-²

< Greek, combining form of psȳchḗ breath, spirit, soul, mind; akin to psȳ́chein to blow ( psykter )

Example Sentences

The film is part psycho kidnapping horror, part shark thriller and part tribute to Madonna’s “Ray of Light.”

From Salon • Jun. 8, 2025

Then from there we landed on the psycho idea.

From Los Angeles Times • Aug. 26, 2024

"People started calling these young girls crazy, hysterical and psycho," the writer explains.

From BBC • Jul. 17, 2024

“No! Bad, psycho governor! No! Sit down! Bad! Stay! Stay away from dogs!”

From New York Times • Apr. 30, 2024

For if Leper was psycho it was the army which had done it to him, and I and all of us were on the brink of the army.

From "A Separate Peace" by John Knowles