eparch
The governor or prefect of a province.
historical
The ruler of an eparchy.
The metropolitan bishop of a province or eparchy.
An Orthodox eparch, or metropolitan bishop, was installed in Polatsk in 992.
Where it comes from
From Ancient Greek ἔπαρχος (éparkhos), from ἐπί (epí, “over”) + ἀρχός (arkhós, “ruler”).
Adapted from the Wiktionary entry eparch (CC BY-SA 4.0).