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

Although the severity of Robert’s mental illness meant several lost years, he had a reprieve at one point for some months, and Hal hopes there may be fertile work left behind.

From The Wall Street Journal • Apr. 17, 2026

This recounts the tragedy of a young man, Richard “Beebo” Russell, who in the throes of mental illness stole a plane and managed to take off into the Pacific Northwest.

From Los Angeles Times • Apr. 13, 2026

Diversion programmes are initiatives that allow alternatives like treatment for people with mental illness who are caught up in the criminal justice system.

From BBC • Apr. 6, 2026

Later, he hints at a troubled childhood; he says his father died but offers no stories about this, and mentions in passing mental illness, without saying whose.

From The Wall Street Journal • Mar. 19, 2026

In the late nineteenth century, alarmed by the inhumane treatment of incarcerated people suffering from mental illness, Dorothea Dix and Reverend Louis Dwight led a successful campaign to get the mentally ill out of prison.

From "Just Mercy" by Bryan Stevenson

Related Words

• insanity
• mental disorder