- a narrow opening produced by cleavage or separation of parts.
- cleavage(def 1).
- Anatomy. a natural division or groove in an organ, as in the brain.
verb (used with object), fis·sured, fis·sur·ing.
- to make fissures in; cleave; split.
verb (used without object), fis·sured, fis·sur·ing.
- to open in fissures; become split.
- any long narrow cleft or crack, esp in a rock
- a weakness or flaw indicating impending disruption or discordfissures in a decaying empire
- anatomy a narrow split or groove that divides an organ such as the brain, lung, or liver into lobesSee also sulcus
- a small unnatural crack in the skin or mucous membrane, as between the toes or at the anus
- a minute crack in the surface of a tooth, caused by imperfect joining of enamel during development
- to crack or split apart
c.1400, from Old French fissure (13c.) and directly from Latin fissura “a cleft,” from root of findere “to split, cleave,” from PIE *bhi-n-d-, from root *bheid- “to split” (cf. Sanskrit bhinadmi “I cleave,” Old High German bizzan “to bite,” Old English bita “a piece bitten off, morsel,” Old Norse beita “to hunt with dogs,” beita “pasture, food”).
- A deep furrow, cleft, or slit.
- A developmental break or fault in the enamel of a tooth.
- A long, narrow crack or opening in the face of a rock. Fissures are often filled with minerals of a different type from those in the surrounding rock.