UMBILICUS

‖Um′bi‐li″cus (?), n. [[L. See Umbilic.]] 1. 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. 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. 3. (Bot.) The hilum.
4. 4. (Zoöl.) (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. 5. (Geom.) (a) One of foci of an ellipse, or other curve. (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.