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

This recounts the tragedy of a young man, Richard “Beebo” Russell, who in the throes of mental illness stole a plane and managed to take off into the Pacific Northwest.

From Los Angeles Times • Apr. 13, 2026

The hospital’s previous building for mental illness had burned down when an inmate set it on fire, so patients were closely watched to make sure they didn’t cause trouble.

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

Related Words

• insanity
• mental disorder