mental illness

American  

noun

1. any of the various forms of psychosis or severe neurosis.

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mental illness British  

noun

1. any of various disorders in which a person's thoughts, emotions, or behaviour are so abnormal as to cause suffering to himself, herself, or other people

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mental illness Scientific  

/ mĕn′tl /

1. Any of various psychiatric disorders or diseases, usually characterized by impairment of thought, mood, or behavior.

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Etymology

Origin of mental illness

First recorded in 1960–65

Example Sentences

President Donald Trump signs a directive to accelerate FDA review of psychedelic drugs for serious mental illness.

From Barron's • Apr. 20, 2026

Carruthers’ case is a perfect storm of capital punishment’s familiar failures: paid informants, information withheld from the jury, untested physical evidence, and the defendant’s mental illness.

From Slate • Apr. 20, 2026

For reasons indistinguishable from mental illness, the U.K. still won’t.

From The Wall Street Journal • Apr. 17, 2026

The suspect, Noemi Guzman, 31, who had a history of mental illness, was pronounced dead at the scene.

From BBC • Apr. 15, 2026

William shared a ward with up to twenty other men who were also battling mental illness.

From "The Woman All Spies Fear" by Amy Butler Greenfield

Related Words

• insanity
• mental disorder