An Etymological Dictionary of the German Language/Wau

by Friedrich Kluge

Wau, m., ‘dyer's weed, weld,’ ModHG. only, from Du. wouw (also in earlier ModHG. Waude); comp. E. weld. From Teut. (Goth. *walda-) are derived Fr. gaude and Span. gualda. In non-Teut. there are no cognates that might explain the early history of the word.