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
There are also plans for a parachute jump by the Army's Golden Knights at the White House ellipse.
—
Nik Popli, Time, 12 June 2025
Jupiter has a tilt of only three degrees, but its orbit is more elliptical than Earth’s, making its analemma a simpler ellipse in its sky.
—Phil Plait, Scientific American, 5 June 2025
Since the Earth’s orbit is an ellipse and not a circle, the planet is about 1.7% closer to the Sun in early January compared with its annual average.
—Steven R. Fassnacht, The Conversation, 17 Feb. 2025
These integrals are rather difficult expressions that started off as parts of an attempt to measure the circumference of an ellipse.
—Richard Jensen, Scientific American, 28 Apr. 2025
See All Example Sentences for ellipse
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Nik Popli, Time, 12 June 2025
Jupiter has a tilt of only three degrees, but its orbit is more elliptical than Earth’s, making its analemma a simpler ellipse in its sky.
—Phil Plait, Scientific American, 5 June 2025
Since the Earth’s orbit is an ellipse and not a circle, the planet is about 1.7% closer to the Sun in early January compared with its annual average.
—Steven R. Fassnacht, The Conversation, 17 Feb. 2025
These integrals are rather difficult expressions that started off as parts of an attempt to measure the circumference of an ellipse.
—Richard Jensen, Scientific American, 28 Apr. 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 1 Jul. 2025.
Copy CitationKids Definition
ellipse
noun
el·lipse
i-ˈlips 
e-
: an oval shape that is a conic section
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