bain-marie
    n 1: a large pan that is filled with hot water; smaller pans
         containing food can be set in the larger pan to keep food
         warm or to cook food slowly

Bain-marie \Bain`-ma`rie"\, n. [F.]
   A vessel for holding hot water in which another vessel may be
   heated without scorching its contents; -- used for warming or
   preparing food or pharmaceutical preparations.
   [1913 Webster]