'Episcopalian' originates from Greek, specifically the word 'episkopos', where 'epi-' meant 'over' and 'skopos' meant 'watcher' or 'observer'; the term passed into Latin as 'episcopus' and into Late Latin/Medieval Latin as 'episcopalis', from which English formed 'episcopal' and then 'Episcopalian' (with the suffix '-ian') to indicate belonging or relation.

'Episcopalian' developed from the adjective 'episcopal' (from Latin 'episcopalis' < Greek 'episkopos') with the addition of the English suffix '-ian' to form a noun/adjective meaning 'of or relating to episcopacy' and later specifically 'a member of the Episcopal Church.'

Initially, the root meant 'overseer' (an individual who watches over); over time the words derived from it came to mean 'relating to bishops or episcopal government' and eventually 'a member of or relating to the Episcopal Church (especially in the U.S.).')