elliptoid

Noun

ellipsoid (plural ellipsoids)

1. 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 x²/a² + y²/b² + z²/c² = 1.
   • Polarizability can be imagined as a three-dimensional ellipsoid centred on the centre of the molecule, as shown in Figure 10.4.2002, John Michael Hollas, Basic Atomic and Molecular Spectroscopy, page 133
2. Such a surface used as a model of the shape of the earth.
   • Here the geoid is thirty meters below the ellipsoid.

See all 5 meanings of ellipsoid