The Collaborative International Dictionary of English v.0.48:

Seraglio \Se*ragl"io\, n. [It. serraglio, originally, an
   inclosure of palisades, afterwards also, a palace, seraglio
   (by confusion with Per. ser[=a]["i]a a palace, an entirely
   different word), fr. serrare to shut, fr. LL. serra a bar for
   fastening doors, L. sera. See Serry, Series.]
   1. An inclosure; a place of separation. [Obs.]
      [1913 Webster]

            I went to the Ghetto, where the Jews dwell as in a
            suburb, by themselves. I passed by the piazza Judea,
            where their seraglio begins.          --Evelyn.
      [1913 Webster]

   2. The palace of the Grand Seignior, or Turkish sultan, at
      Constantinople, inhabited by the sultan himself, and all
      the officers and dependents of his court. In it are also
      kept the females of the harem.
      [1913 Webster]

   3. A harem; a place for keeping wives or concubines;
      sometimes, loosely, a place of licentious pleasure; a
      house of debauchery.
      [1913 Webster]

WordNet (r) 3.0 (2006):

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