The Collaborative International Dictionary of English v.0.48:

Percolator \Per"co*la`tor\, n.
   1. One who, or that which, filters. "[Tissues] act as
      percolators." --Henfrey.
      [1913 Webster]

   2. A type of coffee pot in which the heated water is driven
      by its boiling action up above a porous canister of coffee
      held above the level of the water in the pot, and then
      filters (percolates) back through the coffee thus
      extracting its essence.
      [Webster 1913 Suppl. +PJC]

   3. (Pharmacy) An apparatus for producing an extract from a
      drug by percolation.
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

percolator
    n 1: a coffeepot in which boiling water ascends through a
         central tube and filters back down through a basket of
         ground coffee beans

Moby Thesaurus II by Grady Ward, 1.0:

19 Moby Thesaurus words for "percolator":
   clarifier, colander, cradle, cribble, filter, lixiviator, purifier,
   refiner, refinery, riddle, rocker, screen, sieve, sifter, strainer,
   winnow, winnowing basket, winnowing fan, winnowing machine