Umbilical point.
An umbilic point, likewise called just an umbilic, is a point on a surface at which the arch is the same toward any path.
In the differential geometry of surfaces in three measurements, umbilics or umbilical focuses are focuses on a surface that are locally round. At such focuses the ordinary ebbs and flows every which way are equivalent, consequently, both primary ebbs and flows are equivalent, and each digression vector is a chief heading. The name "umbilic" originates from the Latin umbilicus - navel.
Umbilic focuses for the most part happen as confined focuses in the circular area of the surface; that is, the place the Gaussian ebb and flow is sure. For surfaces with family 0, e.g. an ellipsoid, there must be no less than four umbilics, an outcome of the Poincaré–Hopf hypothesis. An ellipsoid of unrest has just two umbilics.