Reactionary is an ideological, political, and philosophical position that intends to revert society to traditional conservative values. Examples include any position that wants to enforce the gender binary, social Darwinism, unregulated free market capitalism, and kyriarchy. People who subscribe to such ideologies usually lean to the right politically. As such they usually oppose radicalism, multiculturalism, immigration, and social justice, especially the intersectional kind.
A reactionary stance can be seen as the opposite of a revolutionary, progressive, radical, and even sometimes a liberal stance. Proponents of reactionary movements usually propose society returns to a "more innocent age" or "the good old days".