Why are sideburns called sideburns?

Answer 1

they call them sideburns because

SideburnsGeneral Ambrose Everett Burnside from the Union Army wore side whiskers with a moustache, while shaving the hair on his chin. This style was known as Burnside's. The word then became burnsides, and then sideburns.

Ambrose Burnside, a Union General during the civil war, sported a ustache and interesting sidebar whiskers (hair grown down in front of the ears). This style of hair was so distinctive that his name became attached to these whiskers. But there was a catch! The two syllables of his last name were reversed, and sideburn (not Burnside) became the name of these whiskers. Elvis Presley, the 1950s-1970s rock and roll legend, wore sideburns. Before long, many men were growing sideburns to look like Elvis. Too bad that even with (or without) sideburns, they could not perform as well as Elvis.

Answer 2

A Union Army general by the name of Burnside popularized them during America's Civil War.