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

Everything is intended to go to my eldest grandson, who is unable to manage his finances because of severe mental illness.

From MarketWatch ● Sep. 2, 2026

Most are modeled after Britain’s Infanticide Act, which operates on the assumption that a woman who harms her child within a year of giving birth is suffering from a postpartum mental illness.

From Salon ● Sep. 2, 2026

The dotty pumpkins and kaleidoscope rooms of Yayoi Kusama, who has died aged 97, were as vibrant as the artist herself, but her exuberant work was the expression of a long battle with mental illness.

From Barron's ● Aug. 27, 2026

The music’s “demonic” style, with its “fast-paced howling,” could create “a powerful expression of emotional pain and mental illness, among other difficult topics.”

From The Wall Street Journal ● Aug. 21, 2026

At a time when mental illness carried a deep and almost ineradicable stigma, Elizebeth refused to let it create a chasm between her and her husband.

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

Related Words

• insanity
• mental disorder