- noun an oval shape or course
- One of the conic sections, of special importance in astronomy because most orbits are elliptical. Instead of having a single centre, like a circle, an ellipse has two foci and the object being orbited – like the Sun in the solar system – lies at one of them.
- noun an oval-shaped line
- A geometric shape consisting of a closed curve in the shape of an elongated circle. A circle is also a type of ellipse.
Origin & History of “ellipse”
Greek élleipsis meant literally ‘defect, failure’. It was a derivative of elleípein, literally ‘leave in’, hence ‘leave behind, leave out, fall short, fail’, a compound verb formed from the prefix en- ‘in’ and leípein ‘leave’ (which is related to English loan and relinquish). It was borrowed into English in the 17th century as ellipsis in the grammatical sense ‘omission of a word or words’, but its mathematical use for an ‘oval’ (enshrined in the form ellipse, borrowed via French ellipse and Latin ellīpsis) comes from the notion that a square drawn on lines passing vertically and laterally through the centre of an ellipse ‘falls short’ of the entire length of the lateral line.