Is Demency a Word?

noun Madness ; dementia .

Is dementia an English word?

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.

What does it mean to Dement someone?

: to deprive of reason.