diocese

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The district or churches under the jurisdiction of a bishop; a bishopric.

Century Dictionary and Cyclopedia

1. n. A district or division of a country; a province: now obsolete except when used with reference to Norway, an episcopal diocese (stift) of which, as a geographical division of the country, is sometimes regarded as a province, though it has no provincial civil administration.
2. n. Under the Roman empire after Diocletian and Constantine, a subdivision of a prefecture, comprising a number of provinces; hence, a corresponding extent of territory as an ecclesiastical division, including a number of provinces or eparchies, each province again containing a number of parœciæ, which themselves finally came to be called dioceses in the following (modern) sense.
3. n. The district, with its population, falling under the pastoral care of a bishop.

Wiktionary

1. n. Administrative division of the later Roman Empire, starting with the Tetrarchy.
2. n. religion Region administered by a bishop.

GNU Webster's 1913

1. n. (Eccl.) The circuit or extent of a bishop's jurisdiction; the district in which a bishop exercises his ecclesiastical authority.

WordNet 3.0

1. n. the territorial jurisdiction of a bishop