Source : Webster's Revised Unabridged Dictionary (1913)

Interpenetrate \In`ter*pen"e*trate\, v. t.
   To penetrate between or within; to penetrate mutually.

         It interpenetrates my granite mass.      --Shelley.

Interpenetrate \In`ter*pen"e*trate\, v. i.
   To penetrate each the other; to penetrate between bodies or
   their parts.

   {Interpenetrating molding} (Arch.), in late Gothic
      architecture, a decoration by means of moldings which seem
      to pass through solid uprights, transoms, or other
      members; often, two sets of architectural members
      penetrating one another, in appearance, as if both had
      been plastic when they were put together.

Source : WordNet®

interpenetrate
     v 1: penetrate mutually or be interlocked; "The territories of
          two married people interpenetrate a lot" [syn: {permeate}]
     2: spread or diffuse through; "An atmosphere of distrust has
        permeated this administration"; "music penetrated the
        entire building" [syn: {permeate}, {pervade}, {penetrate},
         {diffuse}, {imbue}]