Where does the word 'reactionary' come from?
Solution 1:
The term of French origin appears to have been first used in the current sense by mid-19th century in Marxist use:
Reactionary:
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.
(Etymonline)