amentia
Concise Oxford English Dictionary © 2008 Oxford University Press:
amentia /eɪˈmɛnʃə, ə-/
▶noun Medicine, dated severe congenital mental disability.
– origin ME: from L., lit. ‘madness’, from amens, ament- ‘mad’, from a- ‘without’ + mens ‘the mind’.
'amentia' also found in these Oxford entries:

