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 is an umbrella term for debilitating symptoms that can result in memory loss and impair movement and daily life.

From Barron's • Jun. 15, 2026

It has been spearheaded by neurosurgeon Paul Brennan, of NHS Lothian's department of clinical neurosciences, and Race Against Dementia Fellow Dr Claire Durrant of the University of Edinburgh.

From BBC • Jun. 2, 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

Senile Dementia is a form which is incidental to aged persons, and commences gradually with such symptoms as loss of memory for recent events, dulness of perception, and inability to fix the attention.

From Aids to Forensic Medicine and Toxicology by Robertson, W. G. Aitchison (William George Aitchison )

Related Words

• brain damage
• mental disorder