Definify.com
Webster 1913 Edition
Umbilicus
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1.
(Anat.)
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.
(Gr. & Rom. Antiq.)
An ornamented or painted ball or boss fastened at each end of the stick on which manuscripts were rolled.
Dr. W. Smith.
3.
(Bot.)
The hilum.
4.
(Zool.)
(a)
A depression or opening in the center of the base of many spiral shells.
(b)
Either one of the two apertures in the calamus of a feather.
5.
(Geom.)
(a)
One of the foci of an ellipse, or other curve.
[Obs.]
(b)
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
.