c. 1300, "to perform as an acrobat," also "to fall down," perhaps from a frequentative form of Old English tumbian "dance about, tumble, leap." This is of unknown origin but apparently related to Middle Low German tummelen "to turn, dance," Dutch tuimelen "to tumble," Old High German tumon, German taumeln "to turn, reel." Transitive sense from late 14c. Related: Tumbled; tumbling.
"accidental fall," 1716, from tumble (v.). Earlier as "disorder, confusion" (1630s).