Caliph

Webster's Dictionary

(n.) Successor or vicar; - a title of the successors of Mohammed both as temporal and spiritual rulers, now used by the sultans of Turkey.

The Nuttall Encyclopedia

The title adopted by the successors of Mahomet, as supreme in both civil and religious matters. The principal caliphates are: the Caliphate of the East, established by Abubekr at Mecca, transferred to Bagdad by the Abassides (632-1258); the Caliphate of Cordova, established at Cordova by Abderrahman (756-1031); the Caliphate of Egypt, established by the Fatimites (909-1171). It was at Bagdad that Moslem civilisation achieved its final development.