Definition: A type of flat rubber drive belt that is used to turn multiple accessories on the front of an engine. It is called a serpentine belt because of the way it snakes around the various pulleys. Many vehicles now have a single serpentine drive belt because it eliminates the need for several separate V-belts. A spring-loaded pulley maintains tension on the serpentine belt. This does away with the need to retension the belt when it is replaced. Serpentine belts generally last 25% to 50% longer than conventional V-belts.