Word Origin & History
U.S. colloquial shortening of Britisher or Briton, 1901, formerly (like Britisher) highly offensive to Englishmen traveling in the States, who regarded it as yet another instance of the "odious vulgarism" of the Americans, but Bret and Bryt were common O.E. words for the (Celtic) Britons and survived
until c.1300. In O.Fr., Bret meant "British, Breton; cunning, crafty; simple-minded, stupid."