Is it farther or further?
lip or lip-like part, 1816, in various anatomical and zoological uses, from Latin labrum, cognate with labium "lip" (see lip (n.)). Also noted mid-15c. as the name of some herb.
labrum la·brum (lā'brəm)n. pl. la·bra (-brə) A lip-shaped anatomical edge, rim, or structure.