ellipse

noun

el·​lipse i-ˈlips 

e-

1

a

: 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

• 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 Plaza Hotel, by architect Johan Anrys, of the Belgian firm 51N4E, starts as an ellipse at its base and morphs into a rectangle at its crown. — Fred A. Bernstein, Architectural Digest, 4 Nov. 2026

Instead of a major aesthetic reinvention, the Daniel Roth debuted in the distinctive double-ellipse case and tourbillon architecture that made Roth a household name. — Paige Reddinger, Robb Report, 1 Nov. 2026

Anticipated flights of the vehicles will travel outside of the landing ellipse to regions of interest within a broader exploration zone. — Leonard David, Space.com, 15 Oct. 2026

Up here, on the tundra of Alaska’s North Slope, the summer sun dances in an unending ellipse. — Jordan McGillis, Washington Post, 18 July 2026

Word History

Etymology

Greek elleipsis

First Known Use

circa 1753, in the meaning defined at sense 1a

Rhymes for ellipse

• airships
• airstrips
• clerkships
• eclipse
• equips
• filmstrips
• gunships
• judgeships
• lightships
• outstrips
• parsnips
• spaceships

Kids Definition

ellipse

noun

el·​lipse i-ˈlips 

e-

: an oval shape that is a conic section