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

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

Members of the Goldman family had been fighting over money since the 1980s, lobbing accusations of cheating and fraud and mental illness.

From The Wall Street Journal ● Sep. 5, 2026

This week Quentin Fottrell — the Moneyist — helped a 72-year-old widow who provides monthly financial support to her grandson because his mental illness has left him unable to manage his own affairs.

From MarketWatch ● Sep. 4, 2026

The service for which he had been destined had been against Force, the mental illness of humanity.

From "The Once and Future King" by T. H. White

Related Words

• insanity
• mental disorder