"one affected by amnesia," 1913 (as an adjective from 1885), from amnesia (q.v.).
Entries linking to amnesiac
amnesia n.
"loss of memory," 1786 (as a Greek word in English from 1670s), Modern Latin, from Greek amnesia "forgetfulness," from a- "not" (see a- (3)) + mnesi- "remembering" (found only in compounds), from stem of mnasthai "to recall, remember," which is related to mnemnon "mindful," mneme "memory" (from PIE root *men- (1) "to think"). The usual compound in Greek was amnestia, but this had a specialized sense of "forgetfulness of wrong" (see amnesty).