Definition
A theoretical figure whose dimensions closely approach the dimensions of the GEOID. The exact dimensions are determined by various considerations of the section of the EARTH's surface considered. The SPHEROIDS of Bessel, Clarke, Delambre, Everest, Hayford, Helbert and others have been adopted as reference spheroids in geodetic work by different countries. Also called spheroid of reference, or ellipsoid of reference. See also SPHEROID: OBLATE.