The Collaborative International Dictionary of English v.0.48:

Islamic \Islamic\ adj.
   of or pertaining to Islamism; as, Islamic art.

   Syn: Muslim, Moslem.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Mohammedan \Mo*ham"med*an\, a. [From Mohammed, fr. Ar.
   muh['a]mmad praiseworthy, highly praised.]
   Of or pertaining to Mohammed, or the religion and
   institutions founded by Mohammed; in the latter sense,
   synonymous with Islamic, the term preferred by Moslems.
   [Written also Mahometan, Mahomedan, Muhammadan, etc.]
   [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

Islamic
    adj 1: of or relating to or supporting Islamism; "Islamic art"
           [syn: Muslim, Moslem, Islamic]