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

Emma then revealed Bruce's frontotemporal dementia diagnosis in February 2023. —Gabrielle Rockson, People.com, 12 Mar. 2025

Caring for someone with dementia is extremely demanding and not a one-person job. —Dana Feldman, Forbes, 12 Mar. 2025

Emma Heming Willis is a Hollywood advocate for caretakers Since her husband's 2023 dementia diagnosis, Heming has emerged as an outspoken advocate for caretakers despite her reserved nature. —Jay Stahl, USA TODAY, 11 Mar. 2025

The documentary Where is Wendy Williams? which first aired in February 2024, revealed that she had been diagnosed with primary progressive aphasia and frontotemporal dementia, conditions that impact speech, comprehension and overall cognitive abilities. —Faisal Kutty, Newsweek, 11 Mar. 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