Pronunciation: (i-lips'), [key]
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: (x2/a2) + (y2/b2) = 1. If a = b the ellipse is a circle. See diag. under conic section.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.