Burnside n 1: United States general in the American Civil War who was defeated by Robert E. Lee at the Battle of Fredericksburg (1824-1881) [syn: {A. E. Burnside}, {Ambrose Everett Burnside}] 2: beard grown down the side of a man's face in front of the ears (especially when the rest of the beard is shaved off) [syn: {sideburn}, {mutton chop}, {side-whiskers}]