'archdiocese' originates from Medieval Latin, specifically the word 'archidioecesis', formed from Greek elements 'archi-' meaning 'chief' and 'dioikesis' meaning 'administration' or 'management'.

'archdiocese' was formed by combining 'archi-' (from Greek 'arkhí-', 'chief') with 'diocese', which comes from Latin 'dioecesis' and Greek 'dioikesis' (διοίκησις, 'administration'). The Medieval Latin compound 'archidioecesis' eventually entered English as 'archdiocese'.

Initially it referred broadly to a chief administrative district ('chief administration'); over time it became specialized to mean specifically the chief ecclesiastical district under an archbishop and, by extension, the office or institution of that archbishop.