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

Penny’s history as a student and Marine The case against Penny stemmed from the death of Neely, a 30-year-old street artist who struggled with homelessness, mental illness and drugs, on a New York City subway car on May 1, 2023. —Eric Levenson, CNN, 10 Dec. 2024

Daniel Penny was found not guilty of criminally negligent homicide Monday in the chokehold killing of Jordan Neely on a Manhattan F train — bringing closure in the polarizing case that provoked heated debates about vigilantism, mental illness and subway safety. —Molly Crane-Newman, New York Daily News, 9 Dec. 2024

The center helps people with mental illness live meaningful lives. —John Johnston, The Enquirer, 6 Dec. 2024

Despite the urgency, in 2022, almost 50% of adults with a mental illness did not receive any care in the previous year. —Surabhi Bhandari, Forbes, 3 Dec. 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