Definition - What does Shunt mean?
In IT, a shunt is a conductive sleeve placed over a set of jumper pins to close or open an electrical circuit. Many of these items are made of plastic or similar materials.
Techopedia explains Shunt
The role of the shunt is to enclose the metal jumper pieces or pins. These can change the setup of a motherboard or circuit board. It is common to see jumpers enclosed in a shunt on a circuit board. The jumper pins are arranged in jumper blocks that have particular contact points enclosed in the shunt. By putting on the jumper, users make an electrical connection that can change things like CPU speed, and generally configure elements of a board or items like sound cards.