geometry - the pure mathematics of points and lines and curves and surfaces

plane figure, two-dimensional figure - a two-dimensional shape

ellipse, oval - a closed plane curve resulting from the intersection of a circular cone and a plane cutting completely through it; "the sums of the distances from the foci to any point on an ellipse is constant"

parabola - a plane curve formed by the intersection of a right circular cone and a plane parallel to an element of the curve

hyperbola - an open curve formed by a plane that cuts the base of a right circular cone