A state of open, often prolonged fighting; a battle or war. A state of disharmony between incompatible or antithetical persons, ideas, or interests; a clash. Psychology A psychic struggle, often unconscious, resulting from the opposition or simultaneous functioning of mutually exclusive impulses, desires, or tendencies. Opposition between characters or forces in a work of drama or fiction, especially opposition that motivates or shapes the action of the plot. To be in or come into opposition; differ. Archaic To engage in warfare.