A style of facial hair with hair growing next to the ear down to the bend in the jaw
His left sideburn was longer than the other one.
(Kozmetik) Sideburns (or colloquially sideboards or mutton chops) are patches of facial hair on the sides of a man's face, in front of the ears. They were originally called burnsides after Ambrose Burnside. His hairstyle connected thick sideburns via the moustache but left the chin clean-shaven