A closed curve, the locus of a point such that the sum of the distances from that point to two other fixed points (called the foci of the ellipse) is constant; equivalently, the conic section that is the intersection of a cone with a plane that does not intersect the base of the cone.
To remove from a phrase a word which is grammatically needed, but which is clearly understood without having to be stated.
A surface, all of whose cross sections are elliptic or circular (including the sphere), that generalises the ellipse and in Cartesian coordinates (x, y, z) is a quadric with equation x²/a² + y²/b² + z²/c² = 1.
Such a surface used as a model of the shape of the earth.
Shaped like an ellipse; elliptical.
Having the tridimensional shape of an ellipse rotated on its long axis.
Of or pertaining to an ellipse; elliptic.