The Collaborative International Dictionary of English v.0.48:

Bay window \Bay" win"dow\
   1. (Arch.) A window forming a bay or recess in a room, and
      projecting outward from the wall, either in a rectangular,
      polygonal, or semicircular form; -- often corruptly called
      a bow window.

   Syn: bay window, bow window, bow-window.
        [1913 Webster + WordNet 1.5]

   2. a protruding abdomen. [informal]

   Syn: belly, paunch, pot, potbelly, corporation, tummy.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

bay window
    n 1: slang for a paunch [syn: pot, potbelly, bay window,
         corporation, tummy]
    2: a window that sticks out from the outside wall of a house
       [syn: bay window, bow window]

Moby Thesaurus II by Grady Ward, 1.0:

64 Moby Thesaurus words for "bay window":
   abdomen, abomasum, bay, beerbelly, belly, bow window, breadbasket,
   casement, casement window, corporation, craw, crop, diaphragm,
   embonpoint, fan window, fanlight, first stomach, gizzard, grille,
   gullet, gut, honeycomb stomach, kishkes, lancet window, lantern,
   lattice, light, louver window, manyplies, maw, midriff, omasum,
   oriel, pane, paunch, picture window, pod, port, porthole, pot,
   potbelly, potgut, psalterium, pusgut, rennet bag, reticulum,
   rose window, rumen, second stomach, skylight, spare tire, stomach,
   swagbelly, third stomach, transom, tum-tum, tummy, underbelly,
   ventripotence, wicket, window, window bay, window glass,
   windowpane