In a speech denouncing the GOP, the DNC, and anybody else who he didn't like, Theodore Roosevelt said the following:
I merely want to discuss the difference of policy between the Progressive and the Democratic Party and to ask you to think for yourselves which party you will follow. I will say that, friends, because the Republican Party is beaten. Nobody need to have any idea that anything can be done with the Republican Party.
When the Republican Party - not the Republican Party - when the bosses in the control of the Republican Party, the Barneses and Penroses, last June stole the nomination and wrecked the Republican Party for good and all; I want to point out to you nominally they stole that nomination from me, but really it was from you. They did not like me, and the longer they live the less cause they will have to like me. But while they do not like me, they dread you. You are the people that they dread. They dread the people themselves, and those bosses and the big special interests behind them made up their mind that they would rather see the Republican Party wrecked than see it come under the control of the people themselves. So I am not dealing with the Republican Party. There are only two ways you can vote this year. You can be progressive or reactionary. Whether you vote Republican or Democratic it does not make any difference, you are voting reactionary.
It is important to keep in mind here, that the "party bosses" at the time that were against statist Roosevelt, they were the exact opposite of then of what they are today. That's what he is whining about, but keep in mind that in the end he did win and the GOP became a statist party. Could you imagine today, if we didn't have to worry that the GOP was going to shaft us over Obamacare? What would it be like if we didn't have to say one word, and knew that the Republicans were going to fight this hard against the forces of big government? That's how it was back then. Theodore Roosevelt would be proud of today's Republican Party for not listening to the forces of limited government. "Those guys are just reading their Constitutions, you don't pay any attention to them, they're just reactionaries".
Now, about this word "reactionary". It's important to focus in on because it's a key word that gives you insight into the person who is using it. Just be careful about what your insights are. Roosevelt was not a communist. He wrote about communists, and he hated communists. While they also claim to stand for "progress", communism is the wrong kind of "progress". It's the wrong utopia. This utopia is better than that utopia.
So what does he mean by the word "reactionary" then? Roosevelt means, obviously, that while he is "making progress" toward progressive(not communist) utopia and the biggest government that man has ever seen, you are "reacting" to his proposals to progress, and you are the enemy. The reactionary enemy of progress. You're "reacting", specifically with outdated ideas, which is what makes you a reactionary. You have nothing new to add. You and your ideas are old. Old and tired. Worn out. You're a has-been. Your constitution is a has-been. You're clinging to your guns and your bibles and your antipathy toward others. To use TR's own words, your ideas of Federalism are "the old flint-lock, muzzle-loaded doctrine of States' rights." The word has more depth than just simple "act-react". It's deeply ideological across multiple ideologies. A fascist would likely call people a reactionary too, as the fascists also love big government and view big government as the ultimate in progress.
A quick web search for the word reactionary returns this as one of the top results, and confirms what I am saying. TR could call you a lover of the outdated and "flint-lock, muzzle-loaded" ideas of states rights, and spend hours lecturing you on why we should move on from the constitution, or he could just do it in one word. It saves him time.
There are no communists on Mount Rushmore. There is one Republican, the first Republican, there are two Founding Fathers, and then there's a lowly progressive. "Reactionary" is every bit a communist word as it is a progressive word. You're standing in the way of progress! Stop being a reactionary already.
But here is the really fun question: If Theodore Roosevelt hated Communists so much, why (and more importantly) how did he and other progressives of his ilk come to use the word "reactionary" so often? That's a question for another day.