DIOCESIS (plural DIOCESES) is the Latin word for and the etymological root of modern words for Diocese -See that article, both as a Roman administrative level AND as the ecclesiastical circonscription of a Bishop. In some Christian churches, the diocese is an administrative territorial unit governed by a bishop, sometimes also referred to as a bishopric or episcopal see, though more often the term episcopal see means the office held by the bishop. ... A bishop is an ordained member of the Christian clergy who holds a specific position of authority in any of a number of Christian churches. ...

It stems from the Greek dioikèsis .