dementia

American  

[dih-men-shuh, -shee-uh] / dɪˈmɛn ʃə, -ʃi ə /

noun

dementias plural

1. a condition characterized by progressive, persistent, severe impairment of intellectual capacity, including memory loss, confusion, and emotional instability, resulting from the loss of or damage to neurons in the brain.

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dementia British  

/ -ʃɪə, dɪˈmɛnʃə /

noun

1. a state of serious emotional and mental deterioration, of organic or functional origin

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dementia Scientific  

/ dĭ-mĕn′shə /

1. Deterioration of intellectual faculties, such as memory, concentration, and judgment, sometimes accompanied by emotional disturbance and personality changes. Dementia is caused by organic damage to the brain (as in Alzheimer's disease), head trauma, metabolic disorders, or the presence of a tumor.

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Other Word Forms

Derived Forms

• demential
  adjective

Inflected Forms

Nouns

• dementias
  plural

Etymology

Origin of dementia

First recorded in 1800–10; from Latin dēmentia “madness,” equivalent to dēment- “out of one's mind” ( see dement) + -ia noun suffix

Compare meaning

How does dementia compare to similar and commonly confused words? Explore the most common comparisons:

• dementia vs. senility

Explanation

If your grandfather suffers from dementia, he has a brain disorder that's causing him to gradually lose his memory and become disoriented and confused. Although dementia is most common in elderly people, it's not a normal part of growing older but a syndrome caused by brain disease or injury. Dementia gets its name from the Latin words de, or "without," and mens, or "mind," which join together to mean "madness," although in English, dementia is not the same thing as madness. One example of an illness that causes dementia is Alzheimer's disease.

Example Sentences

Dementia has historically been a hidden disease in which affected individuals are sequestered at home or segregated in day programs or institutions.

From The Wall Street Journal • Jun. 20, 2026

Dementia describes symptoms that impact cognitive abilities, while Alzheimer’s disease is a specific and common type of dementia.

From MarketWatch • May 19, 2026

The mustached southerner, yachting enthusiast and philanthropist, whose empire also included sports clubs, had been suffering from the degenerative disease Lewy Body Dementia.

From Barron's • May 6, 2026

Published online April 3 in Alzheimer's & Dementia, the research included data from about 285,000 patients treated at four NYU Langone hospitals and roughly 85,000 individuals from the Veteran's Health Administration.

From Science Daily • Apr. 22, 2026

Indeed, had a psychiatrist examined him at this time, there is no doubt he would have diagnosed his condition as a beginning Dementia Precox.

From The Foundations of Personality by Myerson, Abraham

Related Words

• brain damage
• mental disorder