Definition

1. Noun:
   • The act of splitting or dividing something: "cleavage" refers to the action of breaking or separating something along a natural line or plane.
   • A division or split between groups or things: It can describe a sharp division or separation, such as between opinions, groups, or social classes.
   • The hollow or indentation between a woman's breasts: In anatomy and common usage, it refers to the visible separation or space between the breasts, especially as revealed by clothing.
   • The repeated cell division of a fertilized egg: In embryology, it denotes the series of mitotic divisions that transform a zygote into a blastula.
   • The splitting of a crystal along a definite plane: In mineralogy, it describes the tendency of a crystalline substance to split along specific structural planes.
   • The breaking of a chemical bond: In chemistry, it refers to the process where a bond in a molecule is broken, producing smaller molecules or fragments.

Usage and Examples

• Referring to a physical split or the act of splitting:
  • The cleavage of the rock revealed beautiful crystal formations inside.
  • The wood has a straight cleavage, making it easy to split for firewood.
• Referring to a division or separation between groups:
  • There is a deep political cleavage within the party on this issue.
  • The debate highlighted the cleavage between traditional and modern values.
• Referring to the space between breasts:
  • Her dress had a neckline that showed a modest amount of cleavage.
• Referring to biological cell division:
  • The biology textbook explained the stages of cleavage in embryonic development.
• Referring to mineral properties:
  • Mica is known for its perfect basal cleavage.
• Referring to a chemical process:
  • The reaction involves the cleavage of the carbon-oxygen bond.

Advanced Usage

• "Cleavage plane": In geology and mineralogy, the flat surface along which a crystal cleaves.
  • Diamonds have cleavage planes that cutters use to shape the gem.
• "Cleavage furrow": In cell biology, the indentation that begins the process of cytokinesis during cell division.
  • The cleavage furrow becomes visible during the telophase stage of mitosis.

Variants and Related Words

• Cleave (verb): To split or divide, especially along a natural line or grain. (e.g., ). Also, to adhere strongly (a different, archaic meaning).
• Cleft (noun/adjective): A space or opening made by splitting; a crack. (e.g., ).

Synonyms

• Division: The action of separating something into parts.
• Split: A division or separation.
• Fissure: A long, narrow crack or opening.
• Separation: The process of moving or being moved apart.
• Schism: A split or division between strongly opposed groups, typically due to differences in opinion or belief.

Idioms and Common Phrases

• "Show cleavage": To wear clothing that reveals the space between the breasts.
  • The dress code advises against showing too much cleavage in the office.
• "A cleavage in society": A profound division within a community or nation.
  • The new policy risks creating a dangerous cleavage in society.

Noun

1. the act of cleaving or splitting
2. the line formed by a groove between two parts (especially the separation between a woman's breasts)
3. (embryology) the repeated division of a fertilised ovum
4. the breaking of a chemical bond in a molecule resulting in smaller molecules
5. the state of being split or cleft
   • there was a cleavage between the liberal and conservative members