\Um`bi*li"cus\, n. [L. See {Umbilic}.]
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.
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. (Zo["o]l.)
   (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 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}.