exothermicadjective
chemistry us/ˌek·soʊˈθɜr·mɪk/[ not gradable ] describes a chemical reaction that produces heat
earth science /ˌek·soʊˈθɜr·mɪk/involving the release or loss of heat:
magnesium starts an exothermic reaction in water.
exothermically
adverb [ not gradable ] us/ˌek·soʊˈθɜr·mɪk·li/