v. t. To penetrate between or within; to penetrate mutually. [ 1913 Webster ]

It interpenetrates my granite mass. Shelley. [ 1913 Webster ]

v. i. To penetrate each the other; to penetrate between bodies or their parts. [ 1913 Webster ]

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. [ 1913 Webster ]