E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
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.
So fair to be partnera
Shakespeare Cymbeline, i. 6
Halliwell gives the following quotation:
Herodias doughter that was a tumb-estre and tumblede before [the king] and other grete lordes of the conré, he granted to geve hure whatevere she would bydde.