The Collaborative International Dictionary of English v.0.48:

Chateaubriand \Chateaubriand\ n.
   a double-thick center cut of beef tenderloin, broiled and
   served with a sauce and potatoes.
   [WordNet 1.5 +PJC]

   Chateau en Espagne[F.], a castle in Spain, that is, a
      castle in the air, Spain being the region of romance.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Chateaubriand
    n 1: French statesman and writer; considered a precursor of the
         romantic movement in France (1768-1848) [syn:
         Chateaubriand, Francois Rene Chateaubriand, Vicomte de
         Chateaubriand]
    2: a very thick center cut of beef tenderloin