/ Dictionary / Index F fusionism: Meaning and Definition of Find definitions for: fu•sion•ism Pronunciation: (fy'zhu-niz"um), [key] — n. Politics. the principle, policy, or practice of fusion. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. fusion bomb fusion reactor Related Content Daily Word Quiz: sinister Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language