A thermal bodysuit is a type of clothing designed to insulate the body and retain heat. It is often worn as an outer layer in cold weather or in cold environments to help the body maintain a comfortable temperature. Thermal bodysuits can be made from a variety of materials, including synthetic fibers like polyester or nylon, as well as natural fibers like wool or cotton. Some thermal bodysuits also have additional features like windproof and waterproof protection to help keep the wearer warm and dry in adverse conditions. They are commonly worn by outdoor enthusiasts, such as hikers, skiers, and snowboarders, as well as people who work outside in cold environments.