The Collaborative International Dictionary of English v.0.48:

Shaitan \Shai"tan\, Sheitan \Shei"tan\, n. [Written also
   sheytan.] [Hind. shait[=a]n, fr. Ar. shai[.t][=a]n.]
   1. Among Mohammedans:
      (a) An evil spirit; the evil one; the devil.
      (b) One of bad disposition; a fiend. [Colloq.]
          [Webster 1913 Suppl.]

   2. (Meteor.) A dust storm. [India]
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

shaitan
    n 1: (Islam) a rebellious jinni who leads men astray [syn:
         shaitan, shaytan]