noun - A flip turn (or tumble turn) is a technique of turning at the walls in a swimming pool. The technique is used to reverse the direction in an efficient and quick manner while using the backstroke or freestyle strokes. It is done when the swimmer reaches the end of the swimming pool but still has one or more lengths to swim.
The technique's development is credited by the International Swimming Hall of Fame to University of Texas swim coach Tex Robertson while he was training Adolph Kiefer for the 1936 Olympics. In competition, flip turns are only permitted during the freestyle and backstroke races.
In contrast, open turns are used in the butterfly and breaststroke races where rules require swimmers to touch the end of the pool with both hands simultaneously before turning back for another length.