walrus: [17] Etymologically, a walrus is probably a ‘whale-horse’. The word seems to have been borrowed from Dutch walrus, which was an inversion of a presumed prehistoric Germanic compound represented by Old English horschwæl and Old Norse hrosshvalr. (The inversion may have been due to the influence of Dutch walvisch ‘whale’ – literally ‘whale-fish’ – but it could also owe something to French influence, since French noun compounds of this sort are often in the reverse order to corresponding Germanic ones.) The element wal- is clearly the same word as whale, and -rus is generally assumed to be horse.
It has, however, been suggested that the horsc- of the Old English term was an alteration of morsa, a name for the walrus of Lappish origin which is also the source of French morse ‘walrus’. => horse, whale
1650s, from Dutch walrus, which was probably a folk-etymology alteration (by influence of Dutch walvis "whale" and ros "horse") of a Scandinavian word, such as Old Norse rosmhvalr "walrus," hrosshvalr "a kind of whale," or rostungr "walrus." Old English had horschwæl, and later morse, from Lapp morsa or Finnish mursu, which ultimately might be the source, much garbled, of the first element in Old Norse rosmhvalr.
