fissure

American  

[fish-er] / ˈfɪʃ ər /

noun

1. a narrow opening produced by cleavage or separation of parts.

2. cleavage.

3. Anatomy. a natural division or groove in an organ, as in the brain.

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verb (used with object)

fissured, fissuring

1. to make fissures in; cleave; split.

verb (used without object)

fissured, fissuring

1. to open in fissures; become split.

fissure British  

/ ˈfɪʃə /

noun

1. any long narrow cleft or crack, esp in a rock

2. a weakness or flaw indicating impending disruption or discord

   fissures in a decaying empire

3. anatomy a narrow split or groove that divides an organ such as the brain, lung, or liver into lobes See also sulcus

4. a small unnatural crack in the skin or mucous membrane, as between the toes or at the anus

5. a minute crack in the surface of a tooth, caused by imperfect joining of enamel during development

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verb

1. to crack or split apart

fissure Scientific  

/ fĭsh′ər /

1. 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.

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Other Word Forms

• fissural adjective
• fissureless adjective
• subfissure noun
• superfissure noun

Etymology

Origin of fissure

1375–1425; late Middle English < Latin fissūra cleaving, cleft, fissure, equivalent to fiss ( us ) divided ( fissi- ) + -ūra -ure

Explanation

A long fine crack in the surface of something is called a fissure. If you see a fissure in the ice on a frozen lake, you'll want to take off your skates and head back to the car. Fissure has its roots in the Latin word fissura, meaning a cleft or crack. If something breaks into fine cracks, you can describe the action with the verb form of fissure. For example, "She watched in horror as the earth fissured beneath her feet, recognizing the signs of an earthquake but powerless to do anything to save herself except throw herself to the ground and hang on."

Example Sentences

Secretary of State Marco Rubio offered a warmer tone at this year’s Munich Security Conference, but European officials say the trans-Atlantic fissure remains.

From The Wall Street Journal • Mar. 22, 2026

Volcanoes in Iceland are capable of producing fissure eruptions that last for years or even decades, consistent with the 14 year platinum signal.

From Science Daily • Mar. 20, 2026

Though most of the film is spent building up to this fissure, “Oh. What. Fun.” stumbles when Claire and her family separate.

From Salon • Dec. 3, 2025

Asked about the fissure, Cortez Masto responded evenly and with diplomacy.

From Los Angeles Times • Oct. 15, 2025

A fissure ran across the length of the ceiling and the far end of the cavern collapsed, burying the altar and the pater.

From "The Mark of Athena" by Rick Riordan

Related Words

• cleavage
• crevice