/ Dictionary / Index F fissi-: Meaning and Definition of Find definitions for: fissi- Pronunciation: [key] a combining form meaning “cleft,” used in the formation of compound words: fissiparous. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Fiske fissile Related Content Daily Word Quiz: vertigo Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language