# ellipse

[ih-lips]

- a plane curve such that the sums of the distances of each point in its periphery from two fixed points, the foci, are equal. It is a conic section formed by the intersection of a right circular cone by a plane that cuts the axis and the surface of the cone. Typical equation: (x2/a2) + (y2/b2) = 1. If a = b the ellipse is a circle.

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## Origin of ellipse^{}

Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

## Related Words

trajectory, rotation, pattern, path, arc, arch, contour, loop, apogee, track, curve, course, circle, locus, lap, round, cycle, perigee, ellipse, swerve## Examples from the Web for ellipse

### Contemporary Examples

### Historical Examples

#### These marks will then represent the diameter of the ellipse across its major axis.

Practical Mechanics for BoysJ. S. Zerbe

#### It is not allowed to move exactly in an ellipse, nor is the earth exactly in the focus.

Great AstronomersR. S. Ball

#### Now it is remarkable that this apparent path is still an ellipse.

Great AstronomersR. S. Ball

#### These points are your centers for scribing the long sides of the ellipse.

Carpentry for BoysJ. S. Zerbe

#### The other two being intersected at an angle, will each be an ellipse.

The Theory and Practice of PerspectiveGeorge Adolphus Storey

## ellipse

- a closed conic section shaped like a flattened circle and formed by an inclined plane that does not cut the base of the cone. Standard equation x ²/ a ² + y ²/ b ² = 1, where 2 a and 2 b are the lengths of the major and minor axes. Area: π ab

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## Word Origin

C18: back formation from ellipsis

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

## Word Origin and History for ellipse

### n.

1753, from French ellipse (17c.), from Latin ellipsis "ellipse," also, "a falling short, deficit," from Greek elleipsis (see ellipsis). So called because the conic section of the cutting plane makes a smaller angle with the base than does the side of the cone, hence, a "falling short." First applied by Apollonius of Perga (3c. B.C.E.).

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Online Etymology Dictionary, © 2010 Douglas Harper

## ellipse

[ĭ-lĭps′]

- A closed, symmetric curve shaped like an oval, which can be formed by intersecting a cone with a plane that is not parallel or perpendicular to the cone's base. The sum of the distances of any point on an ellipse from two fixed points (called the foci) remains constant no matter where the point is on the curve.

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The American Heritage® Science Dictionary
Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

## ellipse

[(i-lips)]

In geometry, a curve traced out by a point that is required to move so that the sum of its distances from two fixed points (called foci) remains constant. If the foci are identical with each other, the ellipse is a circle; if the two foci are distinct from each other, the ellipse looks like a squashed or elongated circle.

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## Note

The New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.