The Collaborative International Dictionary of English v.0.48:

Effendi \Ef*fen"di\, n., [Turk. efendi, fr. Modern Gr. ?, fr.
   Gr. ? a chief. See Authentic.]
   Master; sir; -- a Turkish title of respect, applied esp. to a
   state official or man of learning, as one learned in the law,
   but often simply as the courtesy title of a gentleman.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

effendi
    n 1: a former Turkish term of respect; especially for government
         officials