'episcopacy' originates from Medieval Latin, specifically the word 'episcopatus', where the stem comes from Greek 'episkopos' meaning 'overseer' (from epi- 'over' + skopos 'watcher').

'episcopacy' entered English via Medieval/Modern Latin 'episcopatus' and Old French influences; the Greek 'episkopos' ('overseer') became Latin 'episcopus' ('bishop'), and from the Late Latin/Medieval Latin noun 'episcopatus' came the English 'episcopacy'.

Initially, related words meant 'overseer' or 'the office of an overseer/bishop'; over time the English 'episcopacy' came to mean both the office/term of a bishop and the system of church government led by bishops.