Albion

Many sources suggest that Albion, as a name for Great Britain, comes from the Latin for 'white' – given by Julius Caesar in reference to the White Cliffs of Dover; but most now cast doubt on this idea.

My edition of Brewer's Dictionary of Phrase and Fable (dated 1999) gives it as a possibility, but Infoplease, quoting Brewer's (presumably a later edition) describes it as "quite untenable". "An old Greek treatise," it says,"mentions the islands of Albion [Great Britain] and Ierne [Ireland] three hundred years before the invasion of Caesar. Probably "Albion" or Albany was the Celtic name of all Great Britain, subsequently restricted to Scotland, and then to the Highlands of Scotland." It goes on to suggest that the Carthaginians knew the inhabitants of Great Britain as the Albiones as early as the fifth century BC.

According to Britannica, "The Greeks and Romans probably received the name from the Gauls or the Celts. The name Albion has been translated as 'white land'; and the Romans explained it as referring to the chalk cliffs at Dover (Latin albus, 'white')." In other words, the Romans themselves thought that the name 'Albion' was derived from their word for 'white'; but they were guilty of what Wikipedia would call "false etymology".