Interpenetrate(v. i.) To penetrate each the other; to penetrate between bodies or their parts.
Interpenetrate(v. t.) To penetrate between or within; to penetrate mutually.
Interpenetration(n.) The act of penetrating between or within other substances; mutual penetration.
Interpenetrative(a.) Penetrating among or between other substances; penetrating each the other; mutually penetrative.

Words within interpenetrate