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
2 : ellipsis

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 The main body of the library takes the shape of an ellipse, its curving forms, according to Meckfessel, responding to communal traffic patterns across the site, which links the converging streets of Park Lane and Ridgecrest Road. Mark Lamster, Dallas News, 28 May 2021 For larger or deeper moles, the dermatologist will perform an excision using a scalpel to remove a small ellipse of mole and skin tissue, says Dr. Moshiri. Seraphina Seow, Health.com, 26 May 2021 This is because the shape of the moon's orbit is not a perfect circle, but rather an oval or ellipse, much like a chicken egg. Miriam Fauzia, USA TODAY, 26 May 2021 With these advances, the Perseverance landing ellipse was now a solid 7.7-by-6.6 kilometers. Jatan Mehta, Scientific American, 17 Feb. 2021 Now, Inoue will head back to the lab and look at the ellipse, the most common of the four species found in Poplar Creek this week and a species of greatest conservation concern in Illinois. Morgan Greene, chicagotribune.com, 25 Sep. 2020 Pedestrian gates would be placed to allow access to Pennsylvania Avenue and enclosed park areas including the ellipse, the Park Service said. Washington Post, 3 Nov. 2020 Populations of the ellipse are declining across the state, Inoue said. Morgan Greene, chicagotribune.com, 25 Sep. 2020 At some point in that heads-down work, the organizers will task the teams with writing code that can take control of the actual on-orbit satellite, which will be carving an ellipse around Earth. Sarah Scoles, Wired, 6 Aug. 2020

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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Learn More About ellipse

Time Traveler for ellipse

Time Traveler

The first known use of ellipse was circa 1753

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Statistics for ellipse

Last Updated

7 Jun 2021

Cite this Entry

“Ellipse.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ellipse. Accessed 22 Jun. 2021.

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More Definitions for ellipse



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

More from Merriam-Webster on ellipse

Thesaurus: All synonyms and antonyms for ellipse

Nglish: Translation of ellipse for Spanish Speakers

Britannica.com: Encyclopedia article about ellipse


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