umbery (umber i)

[ umbilic (um-bil'ik), n. and a. [L. umbilicus: see umbilicus.] I. n. In geom., a point of a surface where the radii of curvature are all equal, and a sphere osculates the surface. The number of umbilics, real and imaginary, on a surface of the nth order, is n (10n2-28n+ 22). With the older geometrical writers, an umbilicus is a focus; and an umbilic in the modern sense is analogous to a focus. - Conical umbilic, a conical point of a surface. II. a . Same as umbilical .