As a backhand, a throw to the left that curves right; as a forehand, a throw to the right that curves left.

A piece of track which curves in one direction and then changes direction without any appreciable length of straight track between the two curves.

a curve in one direction immediately followed by a curve in the opposite direction

A curve consisting of two arcs of the same or different radii curving in opposite directions and having a common tangent or a transition curve at their junctions.

Two adjoining horizontal curves of opposite direction.