14 letters · 16 points in Scrabble
verb penetrate mutually or be interlocked
verb spread or diffuse through
originEtymology tree Proto-Indo-European *h₁én Proto-Indo-European *h₁entér Proto-Italic *n̥ter Latin inter Latin inter-bor. English inter- English penetrate English interpenetrate From inter- + penetrate.
Etymology from Wiktionary, CC BY-SA 3.0