Umbilicus
Umbilicus , noun
[L. See Umbilic.]
1.
(Anatomy) The depression, or mark, in the median line of the abdomen, which indicates the point where the umbilical cord separated from the fetus; the navel; the belly button, in humans.
2.
(Greek & Rom. Antiquities) An ornamented or painted ball or boss fastened at each end of the stick on which manuscripts were rolled. — Dr. W. Smith
3.
(Botany) The hilum.
4.
(a) (Zoology) A depression or opening in the center of the base of many spiral shells.
(b)
(Zoology) Either one of the two apertures in the calamus of a feather.
5.
(a) (Geometry) One of the foci of an ellipse, or other curve.
(b)
(Geometry) A point of a surface at which the curvatures of the normal sections are all equal to each other. A sphere may be osculatory to the surface in every direction at an umbilicus. Called also umbilic. [Obsolete]