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

When the National Institute of Mental Health says that half of all American adolescents have experienced mental illness, that isn’t psychiatry advancing as a field.

From The Wall Street Journal • May 10, 2026

“If we have over 60% of the population living outdoors struggling with extreme mental illness or extreme drug addiction, giving them a key is not the solution,” she said.

From Los Angeles Times • May 1, 2026

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

By analyzing families that possessed intergenerational histories of mental illness, the study found striking evidence that bipolar disorder and schizophrenia shared a strong genetic link.

From "The Gene" by Siddhartha Mukherjee

Related Words

• insanity
• mental disorder