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

Rock awkwardly tries to expand this into a story about mental illness.

From Los Angeles Times ● Oct. 7, 2026

The conclusions were made after committee members heard from doctors, advocates and experts from countries that do allow assisted dying for people solely with mental illness, like the Netherlands and Belgium.

From BBC ● Oct. 7, 2026

Supporters of extending the programme to those with mental illness alone argue that not doing so violates their constitutional rights and access to healthcare.

From BBC ● Oct. 7, 2026

"The 18-year-old girl suffering from severe mental illness and near-debilitating trauma no longer exists," her attorneys said.

From BBC ● Sep. 28, 2026

Well, it also took some degree of mental illness, too, but I was suddenly happy for her.

From "The Absolutely True Diary of a Part-Time Indian" by Sherman Alexie

Related Words

• insanity
• mental disorder