Is it farther or further?
"pertaining to the navel," 1540s, from Medieval Latin umbilicalis "of the navel," from Latin umbilicus "navel" (see umbilicus). Umbilical cord attested by 1753 (the native term is navel string).
umbilical um·bil·i·cal (ŭm-bĭl'ĭ-kəl)adj.
Of or relating to the navel.
Relating to the umbilical region of the abdomen.