The Collaborative International Dictionary of English v.0.48:

Harem \Ha"rem\ (h[=a]"r[e^]m; 277), n.[Ar. haram, orig.,
   anything forbidden or sacred, fr. harama to forbid,
   prohibit.] [Written also haram and hareem.]
   1. The apartments or portion of the house allotted to females
      in Mohammedan families.
      [1913 Webster]

   2. The family of wives and concubines belonging to one man,
      in Mohammedan countries; a seraglio.
      [1913 Webster]

WordNet (r) 3.0 (2006):

harem
    n 1: living quarters reserved for wives and concubines and
         female relatives in a Muslim household [syn: harem,
         hareem, seraglio, serail]