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1831, on model of French réactionnaire (19c.), from réaction (see reaction). In Marxist use, "tending toward reversing existing tendencies," opposed to revolutionary and used opprobriously in reference to opponents of communism, by 1858. As a noun, "person considered reactionary," especially in politics, one who seeks to check or undo political action, by 1855.
An extremely conservative person or position that not only resists change but seeks to return to the “good old days” of an earlier social order.