Welsh Legend.a king of Britain and the brother of Manawydan and Branwen: his head was buried at London as a magical defense against invasion. He was sometimes regarded as a sea god or Christian saint.
c.1300, "the husk of wheat, barley, etc., separated from the flour after grinding," from O.Fr. bren "bran, scurf, scales, feces" (12c., Mod.Fr. bran), perhaps connected with Gaulish *brenno- "manure," or with burn. The word also was used 16c. in English for "dandruff flakes."
bran (brān) n. The outer layers of a cereal grain such as wheat, approximately 20 percent of which is indigestible cellulose, used as a source of dietary fiber.