Real Dictionary

tumble
verb: If someone or something tumbles somewhere, they fall there with a rolling or bouncing movement.

tumble in American English
to do somersaults, handsprings, or similar acrobatic or gymnastic feats
intransitive verb: to fall helplessly down, end over end, as by losing one's footing, support, or equilibrium; plunge headlong
noun: an act of tumbling or falling
transitive verb: to cause to fall or roll end over end; throw over or down

tumble in British English
noun: the act or an instance of tumbling
verb: to fall or cause to fall, esp awkwardly, precipitately, or violently