switchback

A railway track on a steep slope in a zigzag formation, in which a train travels in a reverse direction at each switch.

A railway track on which there are steep ascents and descents, a train moving partially or fully by the force of gravity using the momentum generated when descending to travel up an ascending part of the track; especially (British, dated), such a track built for fun rides at an amusement park; a type of rollercoaster.

A flight path consisting of a series of steep ascents and descents, generally flown as a stunt.

A path or road having a series of steep ascents and descents.

A sharp bend in a path or road which causes a traveller to almost reverse their direction of travel, especially one of a series of such bends on an incline; a hairpin bend; also a path or road having such a series of bends.