Source : Webster's Revised Unabridged Dictionary (1913)

Extrusion \Ex*tru"sion\, n.
   The act of thrusting or pushing out; a driving out;
   expulsion.

Source : WordNet®

extrusion
     n 1: something that bulges out or is protuberant or projects from
          a form [syn: {bulge}, {bump}, {hump}, {gibbosity}, {gibbousness},
           {jut}, {prominence}, {protuberance}, {protrusion}, {excrescence}]
     2: squeezing out by applying pressure; "an unexpected extrusion
        of toothpaste from the bottom of the tube"; "the expulsion
        of pus from the pimple" [syn: {expulsion}]