el·​lipse | \ i-ˈlips How to pronounce ellipse (audio) , 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

Illustration of ellipse

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 Kepler himself later rejected this model, after concluding that the orbits of the planets did not form the singular perfect shape of a circle, but instead had the ugly appearance of an ellipse, which can take one of a whole range of shapes. Quanta Magazine, "The Two Forms of Mathematical Beauty," 16 June 2020 In other words, the orbit can be elliptical, but the ellipse can have any orientation in space. Jennifer Ouellette, Ars Technica, "We now have more evidence that Galileo likely never said “And yet it moves”," 17 May 2020 Supermoons occur because the moon orbits the Earth in the shape of an ellipse. Isabel Garcia, House Beautiful, "The Most Incredible Photos of March's Super Worm Moon," 11 Mar. 2020 Instead of sinking below the horizon, the sun moves in an ellipse, perpetually overhead and completely disorienting to anyone who’s never experienced it. BostonGlobe.com, "In Norway, so much beauty — 24 hours a day — and fear of its demise - The Boston Globe," 26 Sep. 2019 Any straight line drawn from one focus to the circumference of the ellipse is reflected to the other focus. Quanta Magazine, "Solution: ‘Is Infinity Real?’," 30 June 2016 An ellipse is a geometric figure that has two foci. Quanta Magazine, "Solution: ‘Is Infinity Real?’," 30 June 2016 The ellipse, heretofore so carefully constructed, appears doomed. Sharon Mizota, latimes.com, "‘Migrant Caravan’ isn’t so different from ‘Disco!’ in this artist’s hands," 1 July 2019 The circle became an ellipse, expanding east, pushed by the gust. Kevin Dupzyk, Popular Mechanics, "Charred and Burned: The School That Turns Firefighters Into Fire Detectives," 4 Oct. 2018

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.

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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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Time Traveler for ellipse

Time Traveler

The first known use of ellipse was circa 1753

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Statistics for ellipse

Last Updated

30 Jun 2020

Cite this Entry

“Ellipse.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ellipse. Accessed 2 Jul. 2020.

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More Definitions for ellipse


How to pronounce ellipse (audio)

English Language Learners Definition of ellipse

: a shape that resembles a flattened circle


el·​lipse | \ i-ˈlips How to pronounce ellipse (audio) \

Kids Definition of ellipse

: a shape that looks like a flattened circle

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More from Merriam-Webster on ellipse

Thesaurus: All synonyms and antonyms for ellipse

Rhyming Dictionary: Words that rhyme with ellipse

Spanish Central: Translation of ellipse

Nglish: Translation of ellipse for Spanish Speakers

Britannica.com: Encyclopedia article about ellipse

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