1. (n.) 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. (n.) An ornamented or painted ball or boss fastened at each end of the stick on which manuscripts were rolled.

3. (n.) The hilum.

4. (n.) A depression or opening in the center of the base of many spiral shells.

5. (n.) Either one of the two apertures in the calamus of a feather.

6. (n.) One of foci of an ellipse, or other curve.

7. (n.) 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.

axis center center of action center of gravity centroid centrum core dead center epicenter heart hub kernel marrow medulla metacenter middle nave navel nub nucleus omphalos pith pivot storm center