Thermal is a term that can refer to a variety of different things. The word can be used to describe WARM temperatures, spas, and ENERGY. WARM is a four letter word that refers to temperatures that are higher than average. SPA is a three letter word that refers to a place where people go to relax and enjoy treatments such as massages and facials. ENERGY is a six letter word that refers to the capacity for doing work or supplying heat. All of these words are related to the term thermal.