# ellipse

noun
el·​lipse | \ i-ˈlips , e-\

## Definition of ellipse

1a : oval
b : a closed plane curve generated by a point moving in such a way that the sums of its distances from two fixed points is a constant : a plane section of a right circular cone that is a closed curve
2

## Illustration of ellipse

ellipse 1b: F, F' foci; P, P', P'' any point on the curve; FP + PF' = FP'' + P''F' = FP' + P'F'

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## The Property of an Ellipse

A closed curve consisting of points whose distances from each of two fixed points (foci) all add up to the same value is an ellipse. The midpoint between the foci is the center. One property of an ellipse is that the reflection off its boundary of a line from one focus will pass through the other. As a result, in an elliptical room, a person whispering at one focus is easily heard by someone at the other. An oval may or may not fit the definition of an ellipse.

## Examples of ellipse in a Sentence

Recent Examples on the Web

The ellipse, heretofore so carefully constructed, appears doomed. The circle became an ellipse, expanding east, pushed by the gust. Imagine seeing a tiny sliver of a line and being asked to draw the ellipse that line was a part of — that was the mathematical challenge. The designers at Hargreaves, Mary Margaret Jones and Brett Seamans, describe their composition as two interlocking squares, bisected by an ellipse. The space telescope will fly in a large ellipse that takes it out beyond the moon and then in close to the Earth to downlink its data. It is laid out as a geometric ellipse, according to a study by mathematician Clark Kimberling, a professor at the University of Evansville. Instead, the moon traces out a geometric figure known as an ellipse. That’s because the moon’s orbit around the Earth is an ellipse, not a circle.

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'ellipse.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

## First Known Use of ellipse

circa 1753, in the meaning defined at sense 1a

## History and Etymology for ellipse

Greek elleipsis

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## Statistics for ellipse

Last Updated

17 Jul 2019

Look-up Popularity

Time Traveler for ellipse

## The first known use of ellipse was circa 1753

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More Definitions for ellipse

ellipse

noun

## English Language Learners Definition of ellipse

: a shape that resembles a flattened circle

ellipse

noun
el·​lipse | \ i-ˈlips \

## Kids Definition of ellipse

: a shape that looks like a flattened circle

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More from Merriam-Webster on ellipse

Rhyming Dictionary: Words that rhyme with ellipse

Thesaurus: All synonyms and antonyms for ellipse

Spanish Central: Translation of ellipse

What made you want to look up ellipse? Please tell us where you read or heard it (including the quote, if possible).

#### desideratum

something desired as essential

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