'pheresis' originates from Greek, specifically the word 'aphairesis' (ἀφαίρεσις), where 'aphairein' meant 'to take away' or 'to remove'.

'pheresis' changed from the longer classical/medical term 'apheresis' (from Greek 'aphairesis') and became used as a clipped or combining form in modern medical English (e.g., 'plasmapheresis').

Initially it meant 'a taking away' in Greek; over time it has retained the core sense of 'removal' but has come to be used especially for medical separations of blood components and as a combining form.