A type of turn in which the swimmer performs a manoeuvre resembling a forward somersault in order to push off from the side of the pool using the feet.
Origin
1940s; earliest use found in The New York Times.
Definition of tumble turn in US English:
tumble turn
noun
A type of turn in which the swimmer performs a manoeuvre resembling a forward somersault in order to push off from the side of the pool using the feet.