'apo' originates from Ancient Greek, specifically the word 'ἀπό' (apó), where 'ἀπό' meant 'away from'.

'apo' entered Late Latin/New Latin and was adopted into English as the combining form 'apo-' used in scientific, technical, and literary compounds; this form has been carried into modern English compound words.

Initially it meant 'away from' in Greek, and over time it has retained this core sense as a prefix meaning 'away, off, separate' in modern usage.