The Collaborative International Dictionary of English v.0.48:

dinner \din"ner\, n. [F. d[^i]ner, fr. d[^i]ner to dine. See
   Dine.]
   1. The principal meal of the day, eaten in some countries
      about midday, but in others (especially in the U. S. and
      in large cities) at a later hour.
      [1913 Webster]

   2. An entertainment; a feast.
      [1913 Webster]

            A grand political dinner.             --Tennyson.
      [1913 Webster]

   Note: Dinner is much used, in an obvious sense, either
         adjectively or as the first part of a compound; as,
         dinner time, or dinner-time, dinner bell, dinner hour,
         etc.
         [1913 Webster]

WordNet (r) 3.0 (2006):

dinner
    n 1: the main meal of the day served in the evening or at
         midday; "dinner will be at 8"; "on Sundays they had a large
         dinner when they returned from church"
    2: a party of people assembled to have dinner together; "guests
       should never be late to a dinner party" [syn: dinner,
       dinner party]

Moby Thesaurus II by Grady Ward, 1.0:

63 Moby Thesaurus words for "dinner":
   Kaffeeklatsch, TV dinner, alfresco meal, ball, banquet, barbecue,
   blowout, breakfast, brunch, buffet supper, clambake,
   cocktail party, coffee break, coffee klatch, collation, cookout,
   costume party, diner, dinner party, donation party, elevenses,
   entertainment, feast, festival, festivity, fete, fish fry,
   garden party, hen party, high tea, hot luncheon, house party,
   house-raising, housewarming, junket, lawn party, lunch, luncheon,
   mash, mask, masque, masquerade, masquerade party, meat breakfast,
   party, petit dejeuner, picnic, regale, shindig, shindy, shower,
   smoker, spread, stag, stag party, supper, surprise party, tea,
   tea break, teatime, tiffin, wiener roast, wienie roast