What is the meaning of Reactionary?

Opposing revolution (such as the French Revolution); favoring a return to a golden age of the past.

Of, pertaining to, participating in, or inducing a chemical reaction.

In reaction to; as a result of.

One who opposes revolution, wanting to reverse it, favoring a return to a past golden age. Often used as a derogatory by revolutionaires.

Source: wiktionary.org