n.
Pronunciation: di- ' men(t)-sh ə , -sh ē - ə
Function: noun
Etymology: Latin, from dement-, demens mad, from de- + ment-, mens mind ― more at MIND
Date: 1806
1 : a usually progressive condition (as Alzheimer's disease) marked by deteriorated cognitive functioning often with emotional apathy
2 : MADNESS , INSANITY <a fanaticism bordering on dementia >
– de · men · tial \ -sh ə l \ adjective