An Etymological Dictionary of the German Language/Annotated/Wau

Wau, masculine, ‘dyer's weed, weld,’ Modern High German only, from Dutch wouw (also in earlier Modern High German Waude); compare English weld. From Teutonic (Gothic *walda-) are derived French gaude and Spanish gualda. In non-Teutonic there are no cognates that might explain the early history of the word.