Caliph

n. title formerly given to a Muslim religious or political leader (also khalif)

For main article see: Caliphate The Caliph (pronounced khaleef in Arabic) is the head of state in a Caliphate, and the title for the leader of the Islamic Ummah, an Islamic community ruled by the Shari'a. It is a transliterated version of the Arabic word which means "successor" or "representative". The early leaders of the Muslim nation following  Muhammad's (570–632) death were called "Khalifat ar-rasul Allah", meaning the political successor to the prophet of God (referring to Muhammad). Some academics prefer to transliterate the term as Khalīf.
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Noun
1. the civil and religious leader of a Muslim state considered to be a representative of Allah on earth; "many radical Muslims believe a Khalifah will unite all Islamic lands and people and subjugate the rest of the world"
(synonym) calif, kaliph, kalif, khalif, khalifah
(hypernym) ruler, swayer
(hyponym) Ali

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

A Spiritual leader in an Islamic state, often the head of state or a powerful clergyman with secular powers.