A body or figure approaching to a sphere, but not perfectly spherical; esp., a solid generated by the revolution of an ellipse about one of its axes.

A body that is shaped like a sphere but is not perfectly round.

A detailed mathematical calculation of the shape of the earth. A spheroid takes into account the non-spherical shape of Earth, and offers a model that increases the accuracy of measurements on its irregular surface.

A body that is almost but not quite a sphere

a shape that is generated by rotating an ellipse around one of its axes; "it looked like a sphere but on closer examination I saw it was really a spheroid"

a circular ellipsoid, for which two of cg the three semiaxes are equal

a mathematical description of the earth

an ellipsoid having two axes of equal length

a solid approaching the figure of a sphere, but not exactly round, formed by the revolution of a semi-ellipsis about its axis

a special case of an ellipsoid where two of the three major axes are equal

A solid that resembles a sphere in geometry. One of the terms used to describe the shape of the earth.

The earth is more or less round. The exact nature of the "more or less" can have significant effects on how well the absolute position of features can be represented on a map. The study of this "more or less" is called geodesy, and its products are spheroids. Spheroids are mathematical representations of the true shape of the earth, from which calculations of location can be made. These calculations are called "datums."

Mathematical figure closely approaching the geoid in form and size and used as a surface of reference for geodetic surveys. A reference spheroid or ellipsoid is a spheroid determined by revolving an ellipse about its shorter (polar) axis and used as a base for geodetic surveys of a large section of the Earth (such as the Clarke spheroid of 1866 which is used for geodetic surveys in the United States).

A 3-dimensional geometric shape based on an ellipse that represents the Earth and approximates the size and shape of the geoid. When mathematically defined it may be used as a datum (surface reference) for geodetic surveys. For example, the North American Datum 1983 (NAD 83) is a spheroid. (See datum and geoid).

an ellipsoid in which two of the three axes are equal. (Contrast to an ellipsoid, in which all three axes may have different lengths.) A spheroid has the equation (x²+y²)/a² + z²/c² = 1

Any figure differing slightly from a sphere; in geodesy one of several mathematical figures closely approaching the undisturbed mean sea level of the earth extending continuously through the continents (geoid) used as a surface of reference for geodetic surveys.

A spheroid is a quadric surface in three dimensions obtained by rotating an ellipse about one of its principal axes.