In Roman Catholic Church - particular Church, or a part of universal Church, a territorial unit established according to Canon Law governed by the diocesan bishop and belonging to the church province called metropolis; in special cases subordinate directly to the Pope; the following are in principle equivalent to a diocese: a territorial prelature, a territorial abbacy, an apostolic vicariate and an apostolic prefecture.

A diocese is a main administrative unit in non-Catholic churches, such as: Orthodox Church, Evangelical Church of the Augsburg Confession, Seventh-Day Adventist Church.

• Territorial units of religious denomination