The spelling of the word "dementate" can be a bit tricky. The IPA phonetic transcription can help understand the spelling better. The word is pronounced as /dɪˈmɛnteɪt/. It is derived from the word dementia, which refers to a decline in cognitive ability. The suffix -ate is often used to indicate a process or action. Thus, dementate means to cause someone to become demented or to cause a decline in cognitive abilities. It is important to be familiar with the spelling and pronunciation of such words to communicate effectively.
To make mad.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.