- (chemistry, physics, uncountable) The quality or state of being exothermic.
2004, Richard A. Jackson, Mechanisms in Organic Reactions, page 137:
- The second step is substantially exothermic and fast; the overall exothermicity ensures that there is no tendency for the reaction to reverse.
- (countable) The release of heat during an exothermic reaction.
1995, Raymond E. March, Practical Aspects of Ion Trap Mass Spectrometry, page 378:
- Because of the unusual methylene substitution selectivities, the exothermicities of the different methylene substitution reactions were calculated from estimated heats of formation of the reactants and heats of formation of the products.