The term HOT TUB can be broken down into three crossword solutions: SPA (3 letters), HOT (3 letters), and TUB (3 letters). A SPA is a location where people go to relax and receive treatments such as massages, facials, and other body treatments. HOT tubs are large, heated pools of water that are used for relaxation and hydrotherapy. They are usually made of wood or plastic and filled with HOT water and jets. Tubs are typically made of metal, plastic, or fiberglass and are used for bathing or soaking.