filter
     n 1: device that removes something from whatever passes through
          it
     2: an electrical device that alters the frequency spectrum of
        signals passing through it
     v 1: remove by passing through a filter; "filter out the
          impurities" [syn: {filtrate}, {strain}, {separate out},
          {filter out}]
     2: pass through; "Water permeates sand easily" [syn: {percolate},
         {sink in}, {permeate}]
     3: run or flow slowly, as in drops or in an unsteady stream;
        "water trickled onto the lawn from the broken hose";
        "reports began to dribble in" [syn: {trickle}, {dribble}]
Source: WordNet® 2.0

filter n. [very common; orig. {{Unix}}, now also in {{MS-DOS}}] A
   program that processes an input data stream into an output data stream
   in some well-defined way, and does no I/O to anywhere else except
   possibly on error conditions; one designed to be used as a stage in a
   `pipeline' (see {plumbing}). Compare {sponge}.


Source: The Jargon File