The etymology of the island's name is obscure. It is known in Latin as "Riduna" but as with the names of all the Channel Islands in the Roman period there is a degree of confusion. "Riduna" may be the original name of Tatihou, while Alderney is conjectured to be identified with "Sarnia". "Alderney"/"Aurigny" is variously supposed to be a Germanic or Celtic name. It may be a corruption of "Adreni" or "Alrene", which is probably derived from an Old Norse word meaning "island near the coast". Alternatively it may derive from three Norse elements: "alda" (swelling wave, roller), "renna" (strong current, race) and "öy" or "-ey" (island).