What is the meaning of Ellipsoid?

A surface, all of whose cross sections are elliptic or circular (including the sphere), that generalises the ellipse and in Cartesian coordinates (x, y, z) is a quadric with equation x/a + y/b + z/c = 1.

Such a surface used as a model of the shape of the earth.

Shaped like an ellipse; elliptical.

Of or pertaining to an ellipse; elliptic.

Having the tridimensional shape of an ellipse rotated on its long axis.

ellipsoid

Source: wiktionary.org