The Collaborative International Dictionary of English v.0.48:

Milieu \Mi`lieu"\ (m[-e]*ly[~e]"), n. [F., fr. mi middle (L.
   medius) + lieu place. See Demi-, Lieu.]
   Environment.

         The intellectual and moral milieu created by multitudes
         of self-centered, cultivated personalities. --J. A.
                                                  Symonds.

         It is one of the great outstanding facts of his
         progressive relation to the elements of his social
         milieu.                                  --J. M.
                                                  Baldwin.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

milieu
    n 1: the environmental condition [syn: milieu, surroundings]