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
The Journal of the American Medical AssociationExamples of dementia in a Sentence
This patient suffers from dementia.
a new study on age-related dementias
Recent Examples on the Web
In other words, there seems to be a dose-dependent response—the higher the flu vaccine dose, the lower the dementia risk.
—Beth Mole, ArsTechnica, 15 May 2026
Her imperious, elderly father Herrmann (Sylvester Groth) has become disinhibited by dementia and is prone to touching his female caretaker (Patrycja Ziółkowska ) inappropriately, a problem Elsa doesn’t want to face any more than Lucy does.
—Leslie Felperin, HollywoodReporter, 15 May 2026
And remember that this is only one component of cutting dementia risk.
—Helen Carefoot, Flow Space, 15 May 2026
One of the largest studies to date found three drinks a week raised the risk for dementia by 15% compared to one drink a week.
—Sandee Lamotte, CNN Money, 14 May 2026
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Beth Mole, ArsTechnica, 15 May 2026
Her imperious, elderly father Herrmann (Sylvester Groth) has become disinhibited by dementia and is prone to touching his female caretaker (Patrycja Ziółkowska ) inappropriately, a problem Elsa doesn’t want to face any more than Lucy does.
—Leslie Felperin, HollywoodReporter, 15 May 2026
And remember that this is only one component of cutting dementia risk.
—Helen Carefoot, Flow Space, 15 May 2026
One of the largest studies to date found three drinks a week raised the risk for dementia by 15% compared to one drink a week.
—Sandee Lamotte, CNN Money, 14 May 2026
See All Example Sentences for dementia
Cite this Entry
“Dementia.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/dementia. Accessed 20 May. 2026.
Copy CitationKids 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)
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