All 11 Uses of

reactionary

in

The Communist Manifesto

Where is the Opposition that has not hurled back the branding reproach of Communism, against the more advanced opposition parties, as well as against its reactionary adversaries?†
*

Nay more, they are reactionary, for they try to roll back the wheel of history.†

The "dangerous class," the social scum, that passively rotting mass thrown off by the lowest layers of old society, may, here and there, be swept into the movement by a proletarian revolution; its conditions of life, however, prepare it far more for the part of a bribed tool of reactionary intrigue.†

REACTIONARY SOCIALISM A. Feudal Socialism Owing to their historical position, it became the vocation of the aristocracies of France and England to write pamphlets against modern bourgeois society.†

For the rest, so little do they conceal the reactionary character of their criticism that their chief accusation against the bourgeoisie amounts to this, that under the bourgeois regime a class is being developed, which is destined to cut up root and branch the old order of society.†

While this "True" Socialism thus served the governments as a weapon for fighting the German bourgeoisie, it, at the same time, directly represented a reactionary interest, the interest of the German Philistines.†

The revolutionary literature that accompanied these first movements of the proletariat had necessarily a reactionary character.†

Therefore, although the originators of these systems were, in many respects, revolutionary, their disciples have, in every case, formed mere reactionary sects.†

By degrees they sink into the category of the reactionary conservative Socialists depicted above, differing from these only by more systematic pedantry, and by their fanatical and superstitious belief in the miraculous effects of their social science.†

But they never cease, for a single instant, to instil into the working class the clearest possible recognition of the hostile antagonism between bourgeoisie and proletariat, in order that the German workers may straightaway use, as so many weapons against the bourgeoisie, the social and political conditions that the bourgeoisie must necessarily introduce along with its supremacy, and in order that, after the fall of the reactionary classes in Germany, the fight against the bourgeoisie itself may immediately begin.†

Definitions:

(1) (reactionary)
someone who is extremely opposed to change; or relating to such a viewpoint

Reactionary is most often used by people who are eager for political or social change to describe people or ideas that they consider exceedingly conservative. People can be referred to as reactionaries or as having reactionary responses. The implication is that such people do not think about what is best. Instead they instinctively react in opposition to any change.
(2) (meaning too rare to warrant focus)
Less commonly, reactionary can just refer to something that changes in response to what happens--such as a chemical.