Saint Lawrence Church, Diocese of Linköping, Sweden.
Pope Pius XI (left) blesses Bishop Stephen Alencastre as fifth Apostolic Vicar of the Hawaiian Islands in a Cathedral of Our Lady of Peace window. In the Catholic Church, the pope as the Supreme Pontiff erects Catholic dioceses throughout the world and appoints their bishops.

The word diocese (z/)[a] is derived from the Greek term διοίκησις meaning "administration". When now used in an ecclesiastical sense, it refers to an administrative territorial entity.[2] In the Western Church, the district is under the supervision of a bishop (who may have assistant bishops to help him or her) and is divided into parishes under the care of priests.[2] This structure of church governance is known as episcopal polity.

The word diocesan means relating or pertaining to a diocese. It can also be used as a noun meaning the bishop who has the principal supervision of a diocese. A diocese also may be referred to as a bishopric or episcopal see, though strictly the term episcopal see refers to the domain of ecclesiastical authority officially held by the bishop, and the term bishopric to the post of being bishop.

An archdiocese (or archiepiscopal see or archbishopric) is more significant than a diocese. An archdiocese is presided over by an archbishop whose see may have or have had importance due to size or historical significance. The archbishop may have metropolitan authority over any other suffragan bishops and their dioceses within his ecclesiastical province.

In the Latter Day Saint movement, the term "bishopric" is used to describe the bishop himself, together with his two counselors, not the ward or congregation of which a bishop has charge.

From about the 13th century until the German mediatization of 1803, the majority of the bishops of the Holy Roman Empire were prince-bishops, and as such exercised political authority over a principality, their so-called Hochstift, which was distinct, and usually considerably smaller than their diocese, over which they only exercised the usual authority of a bishop. Prince-bishops were rare outside the Holy Roman Empire. Two vestiges of this remain: the Catholic Pope is, ex officio, the monarch of the State of Vatican City and the (Catholic) Bishop of Urgell, Spain, is, ex officio, the Spanish Co-Prince of the Co-Principality of Andorra, which is located entirely within his diocese. (The French Co-Prince of the Co-Principality of Andorra is, ex officio, the President of France.)


Dioceses of the Roman Empire, 400 AD

In the later organization of the Roman Empire, the increasingly subdivided provinces were administratively associated in a larger unit, the diocese (Latin dioecesis, from the Greek term διοίκησις, meaning "administration").

With the adoption of Christianity as the Empire's official religion in the 4th century, the clergy assumed official positions of authority alongside the civil governors. A formal church hierarchy was set up, parallel to the civil administration, whose areas of responsibility often coincided.

With the collapse of the Western Empire in the 5th century, the bishops in Western Europe assumed a large part of the role of the former Roman governors. A similar, though less pronounced, development occurred in the East, where the Roman administrative apparatus was largely retained by the Byzantine Empire. In modern times, many dioceses, though later subdivided, have preserved the boundaries of a long-vanished Roman administrative division. For Gaul, Bruce Eagles has observed that "it has long been an academic commonplace in France that the medieval dioceses, and their constituent pagi, were the direct territorial successors of the Roman civitates.[3]

Modern usage of 'diocese' tends to refer to the sphere of a bishop's jurisdiction. This became commonplace during the self-conscious "classicizing" structural evolution of the Carolingian Empire in the 9th century, but this usage had itself been evolving from the much earlier parochia ("parish"), dating from the increasingly formalised Christian authority structure in the 4th century.[4]

Other Languages
Alemannisch: Diözese
العربية: أبرشية
aragonés: Diocesi
asturianu: Diócesis
беларуская: Дыяцэзія
беларуская (тарашкевіца)‎: Дыяцэзія
brezhoneg: Eskopti
català: Diòcesi
čeština: Diecéze
Cymraeg: Esgobaeth
dansk: Stift
Deutsch: Diözese
eesti: Diötsees
español: Diócesis
Esperanto: Episkopujo
euskara: Elizbarruti
français: Diocèse
Frysk: Bisdom
galego: Diocese
hrvatski: Dijeceza
Ido: Diocezo
Bahasa Indonesia: Keuskupan
íslenska: Biskupsdæmi
italiano: Diocesi
עברית: דיוקסיה
Kiswahili: Dayosisi
Kreyòl ayisyen: Dyosèz
Lëtzebuergesch: Diözes
lietuvių: Vyskupija
lingála: Dyosɛ́zi
lumbaart: Diocesi
magyar: Egyházmegye
മലയാളം: രൂപത
Nederlands: Bisdom
日本語: 教区
norsk nynorsk: Bispedømme
occitan: Diocèsi
Plattdüütsch: Bisdom
polski: Diecezja
português: Diocese
română: Dieceză
Scots: Diocese
shqip: Dioqeza
Simple English: Diocese
slovenščina: Škofija
српски / srpski: Бискупија
srpskohrvatski / српскохрватски: Dijeceza
Türkçe: Piskoposluk
українська: Дієцезія
Tiếng Việt: Giáo phận
Winaray: Diosesis
粵語: 教區
中文: 教區