As they relate to ideas and opinions involving politics, morals, property, and manners, these words have widely differing applications. What one person considers moderate, another might term conservative or radical. In meaning, however, conservative refers to a person or state of mind that is disposed to favor gradual rather than sudden change, that wishes to preserve existing conditions and institutions, that is, at most,"cautiously" moderate. In politics and other activities, a moderate is one who opposes views and goals unless they are kept within what he considers reasonable bounds and are not extreme or excessive. A radical favors drastic reforms in politics, morals, manners, or whatever. Each of these words is an adjective as well as a noun: thus one may refer to "a conservative way of dressing," "a moderate degree of success," and "a radical departure from established customs."
Dictionary of problem words and expressions. Harry Shaw. 1975.