Definition of demented adjective from the Oxford Advanced Learner's Dictionary

     

    demented

     adjective
    adjective
    BrE BrE//dɪˈmentɪd//
     
    ; NAmE NAmE//dɪˈmentɪd//
     
    Describing strange traits, Mental and emotional problems
     
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  1. 1(especially British English) behaving in a crazy way because you are extremely upset or worried I've been nearly demented with worry about you. The children have driven me demented today. He was crashing about the house like a demented animal. See related entries: Describing strange traits
  2. 2(old-fashioned or medical) having a mental illness See related entries: Mental and emotional problems
  3. Word Origin mid 17th cent.: past participle of earlier dement ‘drive mad’, from Old French dementer or late Latin dementare, from demens ‘out of one's mind’.
See the Oxford Advanced American Dictionary entry: demented