Entry 2 senses · 2 variants Webster, 1913 Dementate · De·men·tate · IPA /dɪˈmɛnteɪt/ a. v. t. 01 a. Deprived of reason. 1. Deprived of reason. “Arise, thou dementate sinner!” — Hammond. 02 v. t. To deprive of reason; to dement. 1. To deprive of reason; to dement.[R.]