infiltrate, penetrate -- (enter a group or organization in order to spy on the members; "The student organization was infiltrated by a traitor")
penetrate -- (make one's way deeper into or through; "The hikers did not manage to penetrate the dense forest")
penetrate -- (insert the penis into the vagina or anus of; "Did the molester penetrate the child?")
permeate, pervade, penetrate, interpenetrate, diffuse, imbue, riddle -- (spread or diffuse through; "An atmosphere of distrust has permeated this administration"; "music penetrated the entire building"; "His campaign was riddled with accusations and personal attacks")