mental illness

noun

variants or mental disorder or less commonly mental disease

: any of a broad range of medical conditions (such as major depression, schizophrenia, obsessive compulsive disorder, or panic disorder) that are marked primarily by sufficient disorganization of personality, mind, or emotions to impair normal psychological functioning and cause marked distress or disability and that are typically associated with a disruption in normal thinking, feeling, mood, behavior, interpersonal interactions, or daily functioning

mentally ill adjective

Examples of mental illness in a Sentence

Recent Examples on the Web

The late 1970s and early 1980s are remembered for deinstitutionalization — the well-meaning movement to send people with mental illness out of hospitals and into society. —Dan Rodricks, Baltimore Sun, 29 Nov. 2024

Sentencing is set to resume Monday in the trial of Austin police officer Christopher Taylor, who was found guilty of deadly conduct last month in the fatal shooting of a man with a history of mental illness. —Skye Seipp, Austin American-Statesman, 24 Nov. 2024

Penny, a former Marine, is also charged with criminally negligent homicide in the May 1, 2023, killing of Neely, who struggled with mental illness and homelessness. —Janelle Griffith, NBC News, 19 Nov. 2024

Born on March 14, 1933, in Chicago, Quincy Delight Jones was raised in a tumultuous environment marked by the Great Depression and his mother’s mental illness. —Okla Jones, Essence, 4 Nov. 2024

Word History

First Known Use

1724, in the meaning defined above

Kids Definition

mental illness

noun

variants or mental disorder

: a medical condition that is marked by a mild to severe disturbance in the way a person thinks, feels, or acts and is usually accompanied by distress and problems functioning in daily activities or interacting with others

mentally ill adjective

Medical Definition

mental illness

noun

variants or mental disorder also mental disease

: any of a broad range of medical conditions (such as major depression, schizophrenia, obsessive compulsive disorder, or panic disorder) that are marked primarily by sufficient disorganization of personality, mind, or emotions to impair normal psychological functioning and cause marked distress or disability and that are typically associated with a disruption in normal thinking, feeling, mood, behavior, interpersonal interactions, or daily functioning

Some homeless families are also hindered by substance abuse and mental illness.

—Ellen L. Bassuk, Scientific American

Catatonia is usually an expression of mental disorders like bipolar disorder or schizophrenia, but it could also come from other medical problems, such as a brain tumor.

—Forrest Wickman, The Pittsburgh Post-Gazette

… mental diseases such as schizophrenia and manic depression may either involve more than one gene or may result from a complex mix of genetic predisposition and environmental rotten luck.

—Natalie Angier, The New York Times Book Review

mentally ill adjective

mentally ill patients

Mental health workers … perform a wide variety of therapeutic, supportive, and preventative functions for persons who are mentally ill and developmentally disabled.

—Barbara M. Swanson, Careers in Health Care

Legal Definition

mental illness

noun

mental ill·​ness

1

: mental disease

2

: a mental condition marked primarily by sufficient disorganization of personality, mind, and emotions to seriously impair the normal psychological and often social functioning of the individual

called also mental disorder