/ Dictionary / Index D diffusionism: Meaning and Definition of Find definitions for: dif•fu•sion•ism Pronunciation: (di-fy'zhu-niz"um), [key] — n. Anthropol. the theory or principle that diffusion is the main force in cultural innovation and change. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. diffusion diffusive Related Content Daily Word Quiz: reclusive Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language