The Collaborative International Dictionary of English v.0.48:

Foyer \Foy`er"\, n. [F., fr. LL. focarium fireplace. See
   Focus, n.]
   1. A lobby in a theater; a greenroom.
      [1913 Webster]

   2. The crucible or basin in a furnace which receives the
      molten metal. --Knight.
      [1913 Webster]

WordNet (r) 3.0 (2006):

foyer
    n 1: a large entrance or reception room or area [syn:
         anteroom, antechamber, entrance hall, hall,
         foyer, lobby, vestibule]

Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "foyer":
   ancestral halls, chimney corner, entrance, entrance hall,
   entranceway, entry, entryway, family homestead, fireplace,
   fireside, galilee, hearth, hearth and home, hearthstone, home,
   home place, home roof, home sweet home, homestead, household,
   ingle, inglenook, ingleside, lobby, menage, narthex, paternal roof,
   portal, portico, propylaeum, roof, rooftree, stoa, threshold, toft,
   vestibule