The Collaborative International Dictionary of English v.0.48:

Blancmange \Blanc*mange"\ (bl[aum]*m[aum]Nzh; 277), n. [F.
   blancmanger, lit. white food; blanc white + manger to eat.]
   (Cookery)
   A preparation for desserts, etc., made from isinglass, sea
   moss, cornstarch, or other gelatinous or starchy substance,
   with milk, usually sweetened and flavored, and shaped in a
   mold.
   [1913 Webster]

WordNet (r) 3.0 (2006):

blancmange
    n 1: sweet almond-flavored milk pudding thickened with gelatin
         or cornstarch; usually molded