Raymond Williams in Keywords: A Vocabulary of Culture and Society:

    Reactionary has become difficult because it can mean (i) opposed to reforms;
    (ii) wishing to go back to some previous condition; (iii) by application, support-
    ing a particular (right-wing) version of society. There are few difficulties when
    all impulses to change (actions) are from the Left, and all resistance (reactions)
    from the Right. But if, for example, a capitalist party is in an innovating phase, or
    if a fascist party is proposing a new social order, each side can call the other reac-
    tionary: (i) because capitalism and fascism are right-wing, reactionary, as such;
    (ii) because resistance to particular kinds of change, and especially changes and
    innovations in capitalism and capitalist society, is seen as reactionary (wishing to
    preserve or restore some other condition). Thus we can be invited to identify the
    reactionary Right (usually with a sense of the extreme Right, as distinguished
    from progressive or reforming conservatives, as well as from Liberals and the Left)
    but often, also, the reactionary Left (opposing types of change which they see as
    for the worse, or relying on particular senses of the democratic or socialist tradi-
    tion which they oppose to current changes of a different kind).