ELLIPSOID

ellipsoid, ellipsoidal, spheroidal

(adjective) having the nature or shape of an ellipsoid

ellipsoid

(noun) a surface whose plane sections are all ellipses or circles; “the Earth is an ellipsoid”

Source: WordNet® 3.1


Etymology

Noun

ellipsoid (plural ellipsoids)

(mathematics, geometry) 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 = 0.

(geography) Such a surface used as a model of the shape of the earth.

Usage notes

The general case, with semiaxes a, b and c all different, is a triaxial ellipsoid (more rarely, scalene ellipsoid). If two are the same, say b = c, the result is an ellipsoid of revolution, which may be oblate (if a < b) or prolate (a > b). The degenerate case a = b = c is a sphere. An ellipsoid of revolution is also called a spheroid.

Hypernyms

• quadric surface, quadric

Adjective

ellipsoid (comparative more ellipsoid, superlative most ellipsoid)

Shaped like an ellipse; elliptical.

(mathematics) Of or pertaining to an ellipse; elliptic.

(botany) Having the tridimensional shape of an ellipse rotated on its long axis.

Source: Wiktionary


El*lip"soid, n. Etym: [Ellipse + -oid: cf. F. ellipsoide.] (Geom.)

Definition: A solid, all plane sections of which are ellipses or circles. See Conoid, n., 2 (a).

Note: The ellipsoid has three principal plane sections, a, b, and c, each at right angles to the other two, and each dividing the solid into two equal and symmetrical parts. The lines of meeting of these principal sections are the axes, or principal diameters of the ellipsoid. The point where the three planes meet is the center. Ellipsoid of revolution, a spheroid; a solid figure generated by the revolution of an ellipse about one of its axes. It is called a prolate spheroid, or prolatum, when the ellipse is revolved about the major axis, and an oblate spheroid, or oblatum, when it is revolved about the minor axis.

El*lip"soid, El`lip*soi"dal, a.

Definition: Pertaining to, or shaped like, an ellipsoid; as, ellipsoid or ellipsoidal form.

Source: Webster’s Unabridged Dictionary 1913 Edition



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Word of the Day

22 November 2024

SHEET

(noun) (nautical) a line (rope or chain) that regulates the angle at which a sail is set in relation to the wind


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Coffee Trivia

In the 18th century, the Swedish government made coffee and its paraphernalia (including cups and dishes) illegal for its supposed ties to rebellious sentiment.

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