Eparchy is an anglicized Greek word (ἐπαρχία), authentically Latinized as eparchia, which can be loosely translated as the rule or jurisdiction over something, such as a province, prefecture, or territory. It has specific meanings both in politics, history and in the hierarchy of the Eastern Christian churches.
In secular use, the word eparchy denotes an administrative district in the Roman Empire, the Byzantine Empire, or in modern Greece or Cyprus.
In ecclesiastical use, an eparchy is a territorial diocese governed by a bishop of one of the Eastern churches.
Read more about Eparchy: Church Hierarchy, Sources and References