Pronunciation: (fish'ur), [key]
—n., v., -sured, -sur•ing.
1. a narrow opening produced by cleavage or separation of parts.
2. cleavage (def. 1).
3. Anat.a natural division or groove in an organ, as in the brain.
to make fissures in; cleave; split.
to open in fissures; become split.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.