The Collaborative International Dictionary of English v.0.48:

gateau \ga*teau"\, gateau \g[^a]*teau"\(g[.a]*t[=o]"), n. [F.
   cake.] (Cookery)
   Any of various rich and elaborate cakes, particularly a light
   sponge cake having a rich filling or rich icing, such as
   gateau foret noire (Black Forest Cake).
   [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

gateau
    n 1: any of various rich and elaborate cakes

Moby Thesaurus II by Grady Ward, 1.0:

25 Moby Thesaurus words for "gateau":
   Boston cream pie, angel cake, angel food cake, baked Alaska, cake,
   cheesecake, chocolate cake, coffee cake, cupcake, fruitcake,
   genoise, gingerbread, honey cake, jelly roll, jumble, layer cake,
   marble cake, pound cake, savarin, shortcake, spice cake,
   sponge cake, tea cake, white cake, yellow cake