The Collaborative International Dictionary of English v.0.48:

Emir \E"mir\, Emeer \E*meer"\, n. [Ar. em[imac]r, am[imac]r,
   commander: cf. F. ['e]mir. Cf. Admiral, Ameer.]
   An Arabian military commander, independent chieftain, or
   ruler of a province; also, an honorary title given to the
   descendants of Mohammed, in the line of his daughter Fatima;
   among the Turks, likewise, a title of dignity, given to
   certain high officials. Emirship

WordNet (r) 3.0 (2006):

emir
    n 1: an independent ruler or chieftain (especially in Africa or
         Arabia) [syn: emir, amir, emeer, ameer]

Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "emir":
   Esquire, Great Mogul, Master, Mister, Mogul, Muslim rulers, Prinz,
   Sir, atheling, caliph, cham, crown prince, effendi, hakim,
   heir apparent, heir presumptive, imam, khan, king, knez, mirza,
   nawab, nizam, prince, prince consort, prince regent, princeling,
   princes of India, sahib, shahzada, sheikh, sherif, sirdar, sire,
   sirrah, sultan