dement

From Wiktionary

Noun[change]

Singular
dement

Plural
dements

  1. (countable) A dement is an insane person or someone who is suffering from dementia

Verb[change]

Plain form
dement

Third-person singular
dements

Past tense
demented

Past participle
demented

Present participle
dementing

  1. (transitive) If you dement someone, you drive them crazy.