Regressivism is a term used to critically denote policies, ideologies or philosophies that are characterized as advocating a reversal to ones long abandoned or deprecated.
Regressivism, sometimes called "reactionism", is in the same spectrum of political terms as progressivism and conservatism, and is used to distinguish between ideologies that advocate slow changes to those advocating a reversal.
More commonly, political reactionism is a characterization of the backwards political agenda. Many social debates involve some degree of reactionism, where conflicts arise between new scientific issues and their interpreted moral ramifications.
A chemical reaction is a process involving one, two or more substances (called reactants), characterized by a chemical change and yielding one or more product(s) which are different from the reactants.
Classically, chemical reactions encompass changes that strictly involve the motion of electrons, although the general concept of a chemical reaction (in particular the notion of a chemical equation) is applicable to transformations of elementary particles, as well as nuclear reactions.
Reaction rates are related to the concentrations of substances involved in reactions, as quantified by the law of mass action.