/ Dictionary / Index F fissile: Meaning and Definition of Find definitions for: fis•sile Pronunciation: (fis'ul), [key] — adj. capable of being split or divided; cleavable. fissionable. (of a nuclide) capable of undergoing fission induced by low-energy neutrons, as uranium 233 and 235. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: fissile (Thesaurus) fissi- fission Related Content Daily Word Quiz: placid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language