Pronunciation: (hī-pûr'bu-lu),[key] —n.Geom. the set of points in a plane whose distances to two fixed points in the plane have a constant difference; a curve consisting of two distinct and similar branches, formed by the intersection of a plane with a right circular cone when the plane makes a greater angle with the base than does the generator of the cone. Equation: &hyperbola;. See diag. under conic section.