Definitions
1.nounA 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 x2/a2 + y2/b2 + z2/c2 = 0.
2.nounSuch a surface used as a model of the shape of the earth."Here the geoid is thirty meters below the ellipsoid."
3.adjectiveShaped like an ellipse; elliptical.
4.adjectiveOf or pertaining to an ellipse; elliptic.
5.adjectiveHaving the tridimensional shape of an ellipse rotated on its long axis.