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
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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.
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Ars Technica, 18 Mar. 2025
Housed in an 18k yellow gold double ellipse case, the Extra Plat is a reimagining of a 1990 design.
—Cassell Ferere, Forbes, 22 Jan. 2025
That's because all planets orbit the sun in a slight ellipse.
—Jamie Carter, Forbes, 16 Jan. 2025
But the four-ellipse diagram doesn’t have rotational symmetry.
—Jack Murtagh, Scientific American, 14 Jan. 2025
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Ars Technica, 18 Mar. 2025
Housed in an 18k yellow gold double ellipse case, the Extra Plat is a reimagining of a 1990 design.
—Cassell Ferere, Forbes, 22 Jan. 2025
That's because all planets orbit the sun in a slight ellipse.
—Jamie Carter, Forbes, 16 Jan. 2025
But the four-ellipse diagram doesn’t have rotational symmetry.
—Jack Murtagh, Scientific American, 14 Jan. 2025
See All Example Sentences for ellipse
Cite this Entry
“Ellipse.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ellipse. Accessed 22 Apr. 2025.
Copy CitationKids Definition
ellipse
noun
el·lipse
i-ˈlips 
e-
: an oval shape that is a conic section
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