A sheet of matted cotton is a type of fabric made from cotton fibers that are woven together and then matted to create a soft, durable material. The term 'BATT' is an acronym for Bonded All Through Thermal, which is a process used to make the matted cotton fabric. This process involves bonding the cotton fibers together with heat and pressure, creating a strong, lightweight material that is ideal for use in clothing, bedding, and other items.