Interpenetrate

v. i.
  1. To penetrate each the other; to penetrate between bodies or their parts.
  2. 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.