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# ellipsoid

[ih-lip-soid] /ɪˈlɪp sɔɪd/
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 of ellipsoid
1715-1725
From the French word ellipsoïde, dating back to 1715-25. See ellipse, -oid
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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Examples from the Web for ellipsoid
Historical Examples
• The fruit is a small, ellipsoid drupe, which is bluish-black when ripe.

Gerrit Parmile Wilder
• Of the two eggs, one is of an ovoid form, having much the shape of a hen's egg; and the other is an ellipsoid.

• Its form is that of an ellipsoid, with a major axis 26 millimetres in length, while the minor axis measures 11 millimetres.

J. Henri Fabre
• The form of the latter is at first globular, then ellipsoid, and more or less curved.

Mordecai Cubitt Cooke
• Sporangia globose or ovoid to ellipsoid or oblong, erect or sometimes inclined or even nodding.

A. P. Morgan
• ellipsoid, a surface bearing the same sort of relation to a spherical surface as an ellipse bears to a circle.

Various
• A surface expressing the optical relations of such crystals is thus an ellipsoid of revolution about the optic axis.

• Similarly, the dielectric constants of a non-conducting crystal may be expressed by a sphere, spheroid or ellipsoid.

• Therefore the surface is an ellipsoid of revolution having A and B as foci.

• We may, however, assume the ellipsoid with three unequal axes to be an interpolation form.

British Dictionary definitions for ellipsoid

## ellipsoid

/ɪˈlɪpsɔɪd/
noun
1.
1. 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
2. a solid having this shape: the earth is an ellipsoid
Derived Forms
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for ellipsoid
n.

1721; see ellipse + -oid. From 1861 as an adjective (earlier adjective was ellipsoidal).

Online Etymology Dictionary, © 2010 Douglas Harper
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ellipsoid in Science
 ellipsoid   (ĭ-lĭp'soid')    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.
The American Heritage® Science Dictionary
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### Difficulty index for ellipsoid

Few English speakers likely know this word

### Word Value for ellipsoid

0
15
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