/ Dictionary / Index F fissure: Meaning and Definition of Find definitions for: fis•sure Pronunciation: (fish'ur), [key] — n., v., -sured, -sur•ing. —n. a narrow opening produced by cleavage or separation of parts. cleavage (def. 1). a natural division or groove in an organ, as in the brain. —v.t. to make fissures in; cleave; split. —v.i. to open in fissures; become split. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: fissure (Thesaurus) fissirostral fissure of Rolando Related Content Daily Word Quiz: immense Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language