Umbilicus means: Umbilicus: A remnant left on the newborn’s umbilicus
When the umbilical chord is removed from the belly. The navel, also known as the belly or belly.
(in Medical Dictionary)

What else does Umbilicus mean?

Small opening, similar to a navel. It is the hollow at base of shell for some gastropod Mollusks.
(in Merlin Dictionary)