demented

UK: /dɪˈmɛntɪd/ US: /dɪˈmɛntɪd/ ,(di men′tid)

WordReference Random House Learner's Dictionary of American English © 2026

de•ment•ed /dɪˈmɛntɪd/   adj. 

1. crazy;
   insane;
   mad.

WordReference Random House Unabridged Dictionary of American English © 2026

de•ment•ed  (di men′tid), adj. 

1. crazy;
   insane;
   mad.
2. affected with dementia.

• dement + -ed² 1635–45

de•ment′ed•ly, adv. 
de•ment′ed•ness, n. 
Synonyms

• 1. . lunatic, crazed, deranged, unbalanced.

Collins Concise English Dictionary © HarperCollins Publishers::

demented / dɪˈmɛntɪd/ adjective

1. driven mad
2. having dementia

deˈmentedly adverb

deˈmentedness noun

WordReference Random House Unabridged Dictionary of American English © 2026

de•ment  (di ment′), v.t. [Obs.]

1. Psychiatry to make mad or insane.

• Late Latin dēmentāre to deprive of mind, equivalent. to Latin dēment- (stem of dēmēns) out of one's mind (dē- de- + ment- (stem of mēns) mind) + -āre infinitive suffix
• 1535–45

Collins Concise English Dictionary © HarperCollins Publishers::

dement / dɪˈmɛnt/ verb

1. (intransitive) to deteriorate mentally, esp because of old age
2. (transitive) to drive mad

Etymology: 16th Century: from Late Latin dēmentāre to drive mad, from Latin de- + mēns mind