A romping girl, formerly used for a harlot. (Saxon, tumbere, a dancer or romper; Danish, tumle, “to tumble about;” French, tomber; Spanish, tumbar; our tumble.) The word may either be tumbe-boy (one who romps like a boy), or a tumber (one who romps), the word boy being a corruption.
A lady So fair ... to be partner With tomboys.
Halliwell gives the following quotation:
“Herodias dougter that was a tumb-estre, and tumblete before [the king] and other grete lordes of the contré, he granted to geve hure whatevere she would bydde.”
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894