תּוּוָיי, (dial. for תּוּבָיי) = תּוּבְיָה, overflow, inundation. Gen. R. s. 13 כמין ת׳ (‘Rashi’: כהדין ת׳; ed. Leips. תווין, corr. acc.) as from an overflowing river; נהר בבבל ושמו ת׳ וכ׳ (not בבל) there is a river (or canal) in Babylonia which is named Tuvay, and why is it named T.? Because it comes back and inundates once in forty years; Koh. R. to I, 7 תווהא (corr. acc.).