(n) :
		
		originally, a secular office, formally subordinate to -, but de facto the power behind the throne of the (theoretically universal) 
caliph; a hereditary ruler in various 
Muslim states (
sultanate), varying from petty principalities (as in Indonesia and in Yemen), often vassal of a greater ruler, to independent realms, such as 
Oman, 
Brunei, or an empire such as the Turkish 
Ottoman Empire