The Collaborative International Dictionary of English v.0.48:

Eparchy \Ep"arch*y\, n. [Gr. ? the post or office of an ?.]
   A province, prefecture, or territory, under the jurisdiction
   of an eparch or governor; esp., in modern Greece, one of the
   larger subdivisions of a monarchy or province of the kingdom;
   in Russia, a diocese or archdiocese.
   [1913 Webster]

WordNet (r) 3.0 (2006):

eparchy
    n 1: a province in ancient Greece
    2: a diocese of the Eastern Orthodox Church [syn: eparchy,
       exarchate]