Definition that contains plane curve
- circle ellipse in which the two axes are of equal length; a plane curve generated by one point moving at a constant distance from a fixed point
- spiral a plane curve traced by a point circling about the center but at increasing distances from the center
- oval a closed plane curve resulting from the intersection of a circular cone and a plane cutting completely through it
- ellipse a closed plane curve resulting from the intersection of a circular cone and a plane cutting completely through it
- parabola a plane curve formed by the intersection of a right circular cone and a plane parallel to an element of the curve