ex·arch 
(ĕksärk′)
(ĕksärk′)n.
1. A bishop in the Eastern Orthodox Church ranking immediately below a patriarch.
2. The ruler of a province in the Byzantine Empire.
[Late Latin exarchus, an overseer, from Greek exarkhos, from exarkhein, to lead : ex-, ex- + arkhein, to rule.]
ex·archal adj.
exar′chate (ĕksär′kāt), exar′chy (-kē) n.