
1) Deprive of reason 2) Deranged one 3) Drive crazy 4) French word used in English 5) Lunatic of old 6) Madman 7) Make insane 8) Make insane, old-style 9) My Life singer Iris 10) To make mad or insane
Found on
https://www.crosswordclues.com/clue/dement

• (a.) Demented; dementate. • (v. t.) To deprive of reason; to make mad.
Found on
http://thinkexist.com/dictionary/meaning/dement/
De·ment' adjective [ Latin
demens ,
- mentis .] Demented; dementate. [ R.]
J. H. Newman. Found on
http://www.encyclo.co.uk/webster/D/32
De·ment' transitive verb [ Latin
dementare , from
demens ,
-mentis , out of one's mind, mad;
de +
mens mind. See
Mental , and confer
Dementate .] To deprive of reason; to make mad. [ R.]
Bale. Found on
http://www.encyclo.co.uk/webster/D/32

dement Being out of one's mind. From dement, to cause to become mad, raving, crazy; literally, 'out of one's mind'. Legally, a form of mental disorder in which cognitive and intellectual functions of the mind are prominently affected; impairment of memory is an early sign; total recovery is thought to be impossible since organic cerebral disease ...
Found on
http://www.wordinfo.info/words/index/info/view_unit/1289/

to make mad or insane.
Found on
https://www.infoplease.com/dictionary/dement
No exact match found.