An Etymological Dictionary of the German Language/Walfisch
Walfisch, m., ‘whale,’ from the equiv. MidHG. walvisch, OHG. walfisc, m. The first component was orig. sufficient to designate a whale; comp. ModHG., MidHG., and OHG. wal, AS. hwœl, OIc. hvalr, m., ‘whale.’ The early history of Teut. hwala-, ‘whale’ (to which MidHG. walre, OHG. węlira, ‘whale,’ is allied), is obscure. — Walroß, n., ‘walrus,’ from the equiv. Dan. hvalros, as well as Narwal and Wels, are from the same root.