The Collaborative International Dictionary of English v.0.48:

Mahound \Ma`hound\, n.
   A contemptuous name for Mohammed; hence, an evil spirit; a
   devil. [Obs.]
   [1913 Webster]

         Who's this, my mahound cousin ?          --Beau. & Fl.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Mahound
    n 1: the Arab prophet who, according to Islam, was the last
         messenger of Allah (570-632) [syn: Mohammed, Mohammad,
         Muhammad, Mahomet, Mahound]