And Tolkien adapted a pre-existing word, "orc", a variant of "orca", as a name for his race of evil creatures in The Lord of the Rings. That doesn't mean a translator should insert his language's term for "killer whale" every time the English text says "orc". He should call them "orcs" because, though the word may not be new, the meaning is. I sincerely doubt Mr. Carroll intended for us to interpret "mome rath" as " the mother of a fortified farm".