: hair growing on the side of the face in front of the ears
Word History of SIDEBURNS
During the American Civil War there was a Union general named Ambrose Burnside who grew long bushy whiskers on the sides of his face. His appearance first struck the people of Washington, D.C., as he led parades with his regiment of Rhode Island volunteers. Though his later military career had its ups and downs, the general's early popularity encouraged a fashion for such whiskers, which began to be called burnsides. By the 1880s the order of the two words making up burnsides was reversed to give sideburns.