The Collaborative International Dictionary of English v.0.48:

Bey \Bey\ (b[=a]), n. [See Beg a bey.]
   A governor of a province or district in the Turkish
   dominions; also, in some places, a prince or nobleman; a beg;
   as, the bey of Tunis.
   [1913 Webster]

WordNet (r) 3.0 (2006):

bey
    n 1: (formerly) a title of respect for a man in Turkey or Egypt;
         "he introduced me to Ahmet Bey"
    2: the governor of a district or province in the Ottoman Empire

Moby Thesaurus II by Grady Ward, 1.0:

49 Moby Thesaurus words for "bey":
   Dalai Lama, Holy Roman Emperor, Inca, Kaiser, ardri, beg,
   beglerbeg, burgrave, cacique, caesar, cham, collector, czar, dey,
   eparch, exarch, gauleiter, governor, governor-general, kaid, khan,
   khedive, lieutenant governor, mikado, nabob, nawab, negus,
   padishah, palatine, pendragon, pharaoh, proconsul, provincial, rig,
   sachem, sagamore, satrap, shah, sheikh, shogun, stadtholder,
   subahdar, tenno, tetrarch, tycoon, vali, vice-king, viceroy,
   wali