An Etymological Dictionary of the German Language/Ruder
Ruder, n,‘oar, rudder,’ from the equiv. MidHG. ruoder, OHG. ruodar, n.; corresponding to the equiv. Du. roer, AS. rôþer, E. rudder (Goth. *rôþr, n., ‘oar,’ is by chance not recorded); in OIc. with a different suffix rœðe, n., ‘oar,’ while róðr, m., signifies ‘rowing.’ Goth. *rô-þra-, ‘oar,’ belongs to AS. rôwan, str. vb., E. to row, OIc. róa, Du. roeijen, MidHG. rüejen, ruon, all of which signify ‘to row.’ The Teut. root rô appears with the same meaning in the other Aryan languages, as rô, rē̆, er, ar; comp. OIr. rám, Lat. rê-mus, ‘oar’ (ratis, ‘raft’), Gr. ἐ-ρέ-της, ‘rower,’ τρι-ήρης, ‘trireme’; ἐρετμός, ‘oar,’ Sans. arítra-s, ‘oar’; also the Aryan root rê, ‘to push,’ in OSlov. rinąti, rějati, ‘to push,’ Sans. ar, ‘to drive.’ Moreover, E. oar, from AS. âr (OIc. âr) is the relic of another OTeut. term (whence Finn. airo, ‘oar’).