Britain (n.) Look up Britain at Dictionary.com
proper name of the island containing England, Scotland, and Wales, c. 1300, Breteyne, from Old French Bretaigne, from Latin Britannia, earlier Brittania, from Brittani "the Britons" (see Briton). The Old English place-name Brytenlond meant "Wales." If there was a Celtic name for the island, it has not been recorded.