The Collaborative International Dictionary of English v.0.48:

Ameer \A*meer"\, Amir \A*mir"\, n. [See Emir.]
   1. an independent ruler or chieftan (especially in Africa or
      Arabia). Same as Emir. [Obs.]

   Syn: emir, amir, emeer
        [1913 Webster + WordNet 1.5]

   2. One of the Mohammedan nobility of Afghanistan and Scinde.
      [1913 Webster]

WordNet (r) 3.0 (2006):

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