'prelacy' originates from Medieval Latin and Old French, ultimately from Latin 'praelatus' (the past participle of 'praeferre'), with the English nominal suffix '-cy' (via Old French '-cie') forming a noun meaning 'state or office'.

'prelacy' passed into Middle English in forms such as 'prelacie'/'prelacie' from Medieval Latin/Old French and eventually became the modern English word 'prelacy'.

Initially it referred specifically to the office or dignity of a prelate; over time it broadened to include the system or government of prelates but has retained the core sense of clerical office/authority.