What does "umbilicus" mean?

Umbilicus: (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.

Additional senses

  1. 2.(Bot.) The hilum.
  2. 3.(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.
  3. 4.(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.

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