dementia

noun

de·​men·​tia di-ˈmen(t)-shə 

-shē-ə

1

: a usually progressive condition (such as Alzheimer's disease) marked by the development of multiple cognitive deficits (such as memory impairment, aphasia, and the inability to plan and initiate complex behavior)

… dementia is diagnosed only when both memory and another cognitive function are each affected severely enough to interfere with a person's ability to carry out routine daily activities.

—The Journal of the American Medical Association

2

: madness, insanity

a fanaticism bordering on dementia

demential

di-ˈmen(t)-shəl 

-shē-əl

adjective

Synonyms

• aberration
• derangement
• insanity
• lunacy
• madness
• mania
• rage [archaic]

Examples of dementia in a Sentence

This patient suffers from dementia.

a new study on age-related dementias

Recent Examples on the Web

Jim Broadbent, 'Iris' (2002) Featuring Kate Winslet and Judi Dench as famed novelist Iris Murdoch in her younger and older years, the biopic is also a moving drama about the effects of dementia on patients and loved ones. —Brian Truitt, USA TODAY, 28 Feb. 2025

Common signs of dementia, according to an article by Dr. Joanna Woodnutt for Catster, include wandering around aimlessly; going to the wrong door to go out, or to find food; struggling find their way out; becoming stressed even in places that should be familiar; and going potty in the wrong place. —Ross Rosenfeld, Newsweek, 26 Feb. 2025

Only some neurologists specializing in dementia are providing it at this point, Dr. Schindler says. —Amy Norton, SELF, 25 Feb. 2025

Exposure to non-wildfire PM2.5 also increased a person’s risk of dementia, but to a much lesser degree. —Scott Lafee, San Diego Union-Tribune, 25 Feb. 2025

Word History

Etymology

borrowed from Latin dēmentia "derangement, insanity, folly," noun derivative of Latin dēment-, dēmens "out of one's mind, frenzied, insane," from dē- de- + -ment, -mens, adjective derivative of ment-, mens "power of reason, mental balance, mind" — more at mind entry 1

First Known Use

1806, in the meaning defined at sense 1

Phrases Containing dementia

• dementia praecox
• dementia pugilistica
• senile dementia

Rhymes for dementia

• sententiae

Kids Definition

dementia

noun

de·​men·​tia di-ˈmen-chə 

1

: a condition of the brain that is marked especially by a deterioration in the ability to think, reason, or remember

2

: a condition of deteriorating mental functioning

Medical Definition

dementia

noun

de·​men·​tia di-ˈmen-chə 

: a usually progressive condition (as Alzheimer's disease) marked by the development of multiple cognitive deficits (as memory impairment, aphasia, and inability to plan and initiate complex behavior)

demential

-chəl 

adjective