Pronunciation: (mon'iz-um, mō'niz-um),[key] —n. 1. Philos. a. (in metaphysics) any of various theories holding that there is only one basic substance or principle as the ground of reality, or that reality consists of a single element. Cf. dualism (def. 2), pluralism (def. 1a).
b. (in epistemology) a theory that the object and datum of cognition are identical. Cf. pluralism (def. 1b).
2. the reduction of all processes, structures, concepts, etc., to a single governing principle; the theoretical explanation of everything in terms of one principle.
3. the conception that there is one causal factor in history; the notion of a single element as primary determinant of behavior, social action, or institutional relations.