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
In later life, this formative programming can increase the risk of not only mental illnesses like depression, but physical diseases too, such as cancer and obesity.
—
Literary Hub, 20 May 2026
Both sites welcome members with mental illness to spend the day socializing and learning new skills in a relaxed environment.
—Frederick Melo, Twin Cities, 18 May 2026
The Substance Abuse and Mental Health Services Administration estimates that about 30 percent of people experiencing chronic homelessness live with a serious mental illness, and nearly half have a co-occurring substance use disorder.
—Shianne Leclaire, Hartford Courant, 17 May 2026
There was the devastation of extreme mental illness for Avedon’s sister and his second wife.
—Sheri Linden, HollywoodReporter, 17 May 2026
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Literary Hub, 20 May 2026
Both sites welcome members with mental illness to spend the day socializing and learning new skills in a relaxed environment.
—Frederick Melo, Twin Cities, 18 May 2026
The Substance Abuse and Mental Health Services Administration estimates that about 30 percent of people experiencing chronic homelessness live with a serious mental illness, and nearly half have a co-occurring substance use disorder.
—Shianne Leclaire, Hartford Courant, 17 May 2026
There was the devastation of extreme mental illness for Avedon’s sister and his second wife.
—Sheri Linden, HollywoodReporter, 17 May 2026
See All Example Sentences for mental illness
Cite this Entry
“Mental illness.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mental%20illness. Accessed 21 May. 2026.
Copy CitationMedical 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
Ellen L. Bassuk, Scientific AmericanCatatonia 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
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
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
Barbara M. Swanson, Careers in Health Care
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