Illustration of ellipse
- F F' foci
- P P' P'' any point on the curve
- FP + PF' = FP'' + P''F' = FP' + P'F'
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
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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
According to preliminary data, Blue Ghost settled in a location just outside of its 330-foot (100-meter) target landing ellipse, probably due to the last-minute divert maneuvers ordered by the vehicle's hazard avoidance system.
—
Ars Technica, 18 Mar. 2025
That's because all planets orbit the sun in a slight ellipse.
—Jamie Carter, Forbes, 16 Jan. 2025
Herbert’s book helpfully describes the Harkonnen battle arena as triangular in shape rather than the ellipse of the Roman Colosseum, but nearly every other visual detail for Feyd-Rautha’s battle sequence on Giedi Prime needed to be dreamt up from scratch.
—Patrick Brzeski, The Hollywood Reporter, 3 Sep. 2019
The person generating the reflection in the next room must be located somewhere on that ellipse.
—IEEE Spectrum, 30 May 2019
See All Example Sentences for ellipse
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Ars Technica, 18 Mar. 2025
That's because all planets orbit the sun in a slight ellipse.
—Jamie Carter, Forbes, 16 Jan. 2025
Herbert’s book helpfully describes the Harkonnen battle arena as triangular in shape rather than the ellipse of the Roman Colosseum, but nearly every other visual detail for Feyd-Rautha’s battle sequence on Giedi Prime needed to be dreamt up from scratch.
—Patrick Brzeski, The Hollywood Reporter, 3 Sep. 2019
The person generating the reflection in the next room must be located somewhere on that ellipse.
—IEEE Spectrum, 30 May 2019
See All Example Sentences for ellipse
Cite this Entry
“Ellipse.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ellipse. Accessed 14 Apr. 2025.
Copy CitationKids Definition
ellipse
noun
el·lipse
i-ˈlips 
e-
: an oval shape that is a conic section
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