The Collaborative International Dictionary of English v.0.48:

Dumb-waiter \Dumb"-wait`er\, n.
   A framework on which dishes, food, etc., are passed from one
   room or story of a house to another; a lift for dishes, etc.;
   also, a piece of furniture with movable or revolving shelves.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dumbwaiter
    n 1: a small elevator used to convey food (or other goods) from
         one floor of a building to another [syn: dumbwaiter,
         food elevator]