The Collaborative International Dictionary of English v.0.48:

Entr'ee \En`tr['e]e"\, n. [F. See Entry.]
   1. A coming in, or entrance; hence, freedom of access;
      permission or right to enter; as, to have the entr['e]e of
      a house.
      [1913 Webster]

   2. (Cookery) In French usage, a dish served at the beginning
      of dinner to give zest to the appetite; in English usage,
      a side dish, served with a joint, or between the courses,
      as a cutlet, scalloped oysters, etc. [obsolescent]
      [1913 Webster]

   3. the dish which comprises the main course of a meal,
      especially in a restaurant; as, there were many entrees on
      the menu.
      [PJC]

WordNet (r) 3.0 (2006):

entree
    n 1: the principal dish of a meal [syn: entree, main course]
    2: the right to enter [syn: entree, access, accession,
       admission, admittance]
    3: something that provides access (to get in or get out); "they
       waited at the entrance to the garden"; "beggars waited just
       outside the entryway to the cathedral" [syn: entrance,
       entranceway, entryway, entry, entree]
    4: the act of entering; "she made a graceful entree into the
       ballroom"

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "entree":
   access, adit, admission, admittance, antepast, boil, broil,
   casserole, course, cover, culinary masterpiece,
   culinary preparation, dessert, dish, entrance, entremets, entry,
   fry, grill, help, helping, import, importation, importing, in,
   income, incoming, infiltration, ingoing, ingress, ingression,
   input, insertion, insinuation, intake, interpenetration,
   introduction, introgression, intrusion, leakage, main dish,
   open arms, open door, opening, penetration, percolation, place,
   plate, portion, reception, roast, second helping, seepage, service,
   serving, side dish, way