ellipse

American  

[ih-lips] / ɪˈlɪps /

noun

Geometry.

1. a plane curve such that the sums of the distances of each point in its periphery from two fixed points, the foci, are equal. It is a conic section formed by the intersection of a right circular cone by a plane that cuts the axis and the surface of the cone. Typical equation: (x 2 / a2 ) + (y 2 / b2 ) = 1. If a = b the ellipse is a circle.

---

ellipse British  

/ ɪˈlɪps /

noun

1. a closed conic section shaped like a flattened circle and formed by an inclined plane that does not cut the base of the cone. Standard equation x ²/ a ² + y ²/ b ² = 1, where 2 a and 2 b are the lengths of the major and minor axes. Area: π ab

---

ellipse Scientific  

/ ĭ-lĭps′ /

1. A closed, symmetric curve shaped like an oval, which can be formed by intersecting a cone with a plane that is not parallel or perpendicular to the cone's base. The sum of the distances of any point on an ellipse from two fixed points (called the foci) remains constant no matter where the point is on the curve.

---

ellipse Cultural  

1. In geometry, a curve traced out by a point that is required to move so that the sum of its distances from two fixed points (called foci) remains constant. If the foci are identical with each other, the ellipse is a circle; if the two foci are distinct from each other, the ellipse looks like a squashed or elongated circle.

---

Discover More

The orbits of the planets and of many comets are ellipses.

Etymology

Origin of ellipse

First recorded in 1745–55; from French, from Latin ellīpsis ellipsis; or by back formation from the plural ellipses

Compare meaning

How does ellipse compare to similar and commonly confused words? Explore the most common comparisons:

• ellipse vs. hyperbola

Explanation

An ellipse is a closed-plane curve that results from the intersection of a plane cutting through a cone. In other words, it’s an oval. This is a word you'll probably see in geometry class, though it's a shape you can find all over the place. An ellipse is a closed curve that never made it around to a circle. If one thing travels around another in the shape of an ellipse — like the earth around the sun — it has an elliptical orbit. The plural for both ellipse and ellipsis is ellipses — so be careful not to mix up your ovals with your dots.

Example Sentences

“The central space is simply a regular ellipse, and the walls that surround it are vertical,” he would later recall.

From New York Times • Mar. 28, 2024

The sun doesn’t sit at the center of Earth’s ellipse but instead at one focus, a point along the long, or “major,” axis.

From Scientific American • Jun. 30, 2023

Our star’s lopsided locale within Earth’s orbital ellipse means that over the course of a year, our planet’s motion brings it alternately a bit closer to the sun and then farther away again.

From Scientific American • Jun. 30, 2023

With a distinctly contemporary design, the bulbs come in three shapes — large globe, ellipse, and triangular — and can be paired with a specially designed pendant cord, available in white and black.

From The Verge • Sep. 1, 2022

All of a sudden, the ellipse opens up and becomes a parabola.

From "Zero: The Biography of a Dangerous Idea" by Charles Seife

Related Words

• arc
• arch
• contour
• loop
• trajectory