A defense mechanism, operating unconsciously, in which a person adopts affects, ideas, and behaviors that are the opposites of impulses harbored either consciously or unconsciously. For example, excessive moral zeal may be a reaction to strong but repressed asocial impulses.
In psychiatry, defense mechanism in which a person unconsciously develops attitudes and behavior that are contrary to repressed unacceptable drives and impulses, and that serve to conceal them (e.g., a strong moral stance that hides an impulse to lust).
A defense mechanism by which unacceptable unconscious ideas are replaced by the opposite conscious attitude. For instance, a man might make an ostentatious show of affection to a person for whom he has an unconscious hatred.