An @E02035@, constituting one of the stages of a @S05970@ in which a @R05171@ (or, for the first step, the reactants) is converted into the next @R05171@ (or, for the last step, the products) in the @ST06775@ of intermediates between reactants and products.
See also:
rate-limiting step
reaction stage
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1159 [Terms] [Paper]