Greek 'without memory,' from PIE 'to think' — the same root behind 'mind,' 'mental,' 'amnesty,' and 'mnemonic.'
A partial or total loss of memory.
From Modern Latin 'amnesia,' from Greek 'amnesia' (forgetfulness), from 'a-' (not, without) + 'mnesis' (memory, remembrance), from 'mimneskein' (to remember), from PIE *men- meaning 'to think, to remember.' The same PIE root produced 'mind,' 'mental,' 'mentor,' 'mania,' 'mnemonic,' and 'amnesty.' The word was coined or revived