The dictionary definition of 反动 means reactionary, and in the political sense it can also mean someone who is very conservative, as opposed to progressive.
However, it seems that this word is being used in a far broader sense, and with strongly negative connotations. For example, take this passage:
It seems that apart from the last of those four points, all could be used to describe any government, reactionary or not.
Or this passage:
Which describes unequal law instead of reactionary.
So what meanings does 反动 really have? And (although this one seems obvious) is such usage limited to PRC?