An Etymological Dictionary of the German Language/Annotated/Thräne
Thräne, feminine, ‘tear’ (in Swabian and Bavarian Zähre is the popular term), from the equivalent late Middle High German trêne, feminine; properly the plural of the Middle High German singular trahen (contracted trân), masculine; corresponding to Old High German trahan (trân), masculine (Old Saxon trahni, plural), ‘tears’; Teutonic base, trahnu-. The equivalent Middle High German traher recalls Middle High German zaher (see Zähre), so that Teutonic tahru must have had the parallel forms trahru and trahnu. More definite information concerning the early history of Middle High German trahen, traher, cannot be ascertained.