Definition of dement in US English:

dement

noun

archaic
  • A person suffering from dementia.

    • ‘The Picts, to most people outside Scotland, are a totally mysterious and marginal dement in the ancient population of northern Britain.’
    • ‘Nowadays, no sooner is an asylum built than it is filled with maniacs, suicidal melancholics, or senile dements in need of care and treatment.’

Origin

Late 15th century (as an adjective in the sense ‘demented’): from French dément or Latin demens, dement- ‘insane’. The noun use dates from the late 19th century.

Pronunciation

dement

/dəˈment//dəˈmɛnt/