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.