Source : Webster's Revised Unabridged Dictionary (1913)

Dement \De*ment"\, v. t. [L. dementare, fr. demens, -mentis, out
   of one's mind, mad; de + mens mind. See {Mental}, and cf.
   {Dementate}.]
   To deprive of reason; to make mad. [R.] --Bale.

Dement \De*ment"\, a. [L. demens, - mentis.]
   Demented; dementate. [R.] --J. H. Newman.