dementia (n.)youdaoicibaDictYouDict[dementia 词源字典]
1806, from Latin dementia "madness, insanity," literally "a being out of one's mind," from dement-, stem of demens "mad, raving" (see dement) + abstract noun suffix -ia. It existed earlier in an anglicized form, demency (1520s), from French démence. Dementia praecox is a Modern Latin form recorded from 1899 in English, 1891 in German, from French démence précoce (1857). See precocious. [dementia etymology, dementia origin, 英语词源]