a·men·tia 
(ā-mĕnshə, -shē-ə)
(ā-mĕnshə, -shē-ə)n.
Severe intellectual disability. This term belongs to a classification system no longer in use.
[Latin āmentia, mental derangement, from āmēns, āment-, out of one's mind, mentally deranged : ā-, ab-, out of; see AB–1 + mēns, mind; see men-1 in the Appendix of Indo-European roots.]