mental illness

American  

noun

• mental illnesses
  plural

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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Other Word Forms

Noun Inflected Forms

• mental illnesses
  plural

Etymology

Origin of mental illness

First recorded in 1960–65

Example Sentences

See Examples For:

mental illness

Don’t miss: ‘I currently give him $1,000 a month’: My grandson has severe mental illness.

From MarketWatch ● Sep. 14, 2026

It had been due to be extended to people with a mental illness but that is now on hold.

From BBC ● Sep. 11, 2026

Linton had struggled with bipolar disorder for years before the crash and was twice hospitalized due to issues related to her mental illness.

From Los Angeles Times ● Sep. 8, 2026

At the event, Trump highlighted the drugs’ “life-changing potential for those suffering from severe mental illness and depression, including our cherished veterans.”

From The Wall Street Journal ● Sep. 5, 2026

In the hush-hush 1940s, such a public display of mental illness would have spelled the end of Blanche’s career at Langley, even if she had been able to recover from the episode.

From "Hidden Figures" by Margot Lee Shetterly

Related Words

• insanity
• mental disorder