# ellipsoid

## ellipsoid

[ih-lip-soid]
noun
1.
Geometry. a solid figure all plane sections of which are ellipses or circles. Typical equation: (x 2 / a 2 ) + (y 2 / b 2 ) + (z 2 / c 2 ) = 1.
2.

Origin:
1715–25; < French ellipsoïde. See ellipse, -oid

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World English Dictionary
 ellipsoid (ɪˈlɪpsɔɪd) —n a.  a geometric surface, symmetrical about the three coordinate axes, whose plane sections are ellipses or circles. Standard equation: x²/a² + y²/b² + z²/c² = 1, where ±a, ±b, ±c are the intercepts on the x-, y-, and z- axes b.  a solid having this shape: the earth is an ellipsoid ellipsoidal —adj

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Etymonline
Word Origin & History

ellipsoid
1721 (n.); 1861 (adj.), from ellipse + see -oid.
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Science Dictionary
 ellipsoid   (ĭ-lĭp'soid')  Pronunciation Key  A three-dimensional geometric figure resembling a flattened sphere. Any cross section of an ellipsoid is an ellipse or circle. An ellipsoid is generated by rotating an ellipse around one of its axes.
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Encyclopedia Britannica
Encyclopedia

ellipsoid

closed surface of which all plane cross sections are either ellipses or circles. An ellipsoid is symmetrical about three mutually perpendicular axes that intersect at the centre