Reactionary
Etymology
From French "réactionnaire," born in the aftermath of the 1789 Revolution to name those pushing "reaction" against it. The root is Latin "re-" (back) plus "agere" (to do, drive) — a driving-back against the momentum of change.
noun · /ree-AK-shuh-nair-ee/
A person who opposes change and seeks to restore a previous social or political order.
What it names
A precise political label for wanting to turn the clock back, not merely to slow reform down.
Example
The party’s reactionary wing wanted to undo reforms that were decades old.
Related idea
A reactionary wants to restore a vanished past; a conservative merely wants to preserve the present and change slowly — a difference of direction, not just degree.