'antemortal' originates from Latin, specifically the prefix 'ante-' meaning 'before' and 'mortalis' meaning 'subject to death'.

'antemortal' was formed from Late Latin/Medieval Latin elements (compare Late Latin 'antemortalis') and was adopted into Modern English by analogy with terms like 'antemortem' and 'mortal'.

Initially it directly combined the senses 'before' + 'mortal' to mean 'before death'; over time the meaning has remained essentially the same and is used in technical or formal contexts to mean 'pre-mortem'.