mental illness

American  

noun

mental illnesses plural

1. any of the various forms of psychosis or severe neurosis.

---

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

---

mental illness Scientific  

/ mĕn′tl /

1. Any of various psychiatric disorders or diseases, usually characterized by impairment of thought, mood, or behavior.

---

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

All of the essays traffic, to one degree or another, in emotional pain, and some have at their core the grievous dislocations of mental illness.

From The Wall Street Journal ● Jul. 24, 2026

"We already knew psilocybin could be helpful for treating mental illness," Carhart-Harris said.

From Science Daily ● Jul. 22, 2026

But family alone can’t seem to do much to mitigate, let alone cure, mental illness or the impact of childhood trauma.

From Los Angeles Times ● Jul. 8, 2026

Remains were also taken from Polish Jews and Catholics, those with mental illness, political prisoners, Belgian resistance fighters and French and Polish soldiers.

From BBC ● Jun. 17, 2026

Some people think mental illness is a matter of mood, a matter of personality.

From "Every Day" by David Levithan

Related Words

• insanity
• mental disorder