cleavage

cleave +‎ -age

• (Received Pronunciation) IPA^(key): /ˈkliː.vɪd͡ʒ/
• (General American) IPA^(key): /ˈkli.vɪd͡ʒ/
• (General Australian) IPA^(key): /ˈkliː.vɪd͡ʒ/, [ˈklɪi.vɪd͡ʒ]

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• Hyphenation: cleav‧age

cleavage (countable and uncountable, plural cleavages)

1. The act of cleaving or the state of being cleft. [from 19th c.]
   • 1905, Charles Kenneth Leith, “The Observed Relation of Secondary Rock Cleavage to the Parallel Arrangement of Mineral Particles”, in Rock Cleavage (United States Geological Survey Bulletin; no. 239), Washington, D.C.: Government Printing Office, →OCLC, page 51:

     Mineral cleavage is a property of cohesion. The cleavage of the particles themselves and its attitude with reference to the plane of the greatest and mean dimensional axes help to determine the perfection of rock cleavage. The more nearly parallel to the greater dimensions of the particle, and the better the mineral cleavage, the better the rock cleavage produced.

   • 1985 August 24, Robert Butler, “Sex More Punished Than Murder”, in Gay Community News, volume 13, number 7, page 5:

     […] the forces — the internal cleavages over class differences, the desire for "the good life," the white racist flight from the die schwartze — which shattered Jewish working-class community in the generation before mine.

   • 1990, N[eville] J. Price, J[ohn] W. Cosgrove, “Rock Cleavage and Other Tectonic Fabrics”, in Analysis of Geological Structures, Cambridge: Cambridge University Press, →ISBN, page 434:

     It will become apparent from the following discussion that some of the various structures which are grouped together as cleavage may correspond to a schistosity and/or foliation. Accordingly, Wilson defines rock cleavage (and schistosity) as a planar structure, usually distinct from stratification, which permits rocks to be fractured or cleaved into thin slices. Dennis (1977) defines cleavage as a set of closely spaced secondary, planar, parallel fabric elements that impart mechanical anisotropy to a rock without apparent loss of cohesion. This latter definition appears more precise; however, as we shall see, it presents many difficulties in dealing with those forms of cleavage which are mainly defined by foliation or by fractures.

2. The hollow or separation between a woman's breasts, especially as revealed by a low neckline. [from 20th c.]
   • 1946 August 5, “Cinema: Cleavage and the Code”, in Time:

     Low-cut Restoration costumes worn by the Misses Lockwood and Roc (see cut) display too much "cleavage" (Johnston Office trade term for the shadowed depression dividing an actress' bosom into two distinct sections).

   • 2003, Chess Denman, Sexuality: A Biopsychosocial Approach, Basingstoke, Hampshire: Palgrave Macmillan, →ISBN:

     Wendy thought that her therapist was looking down her cleavage and said so. The therapist was mortified and chiefly felt guilty, unsure whether she had been looking down her patient's cleavage or not. On a reflex she assured Wendy that she was not looking down her cleavage and the matter appeared to rest.

   • 2015, Viet Thanh Nguyen, The Sympathizer, New York, N.Y.: Grove Press, →ISBN:

     All this time I kept my gaze fixed on hers, an enormously difficult task given the gravitational pull exerted by her cleavage. While I was critical of many things when it came to so-called Western civilization, cleavage was not one of them.

3. (by extension) Any similar separation between two body parts, such as the buttocks or toes.
   • 2003, Helen Fielding, Olivia Joules and the Overactive Imagination, London: Picador, →ISBN, page 95:

     Half an hour later, she was staring at a large bottom-cleavage, which was protruding from under the bed. / 'Ohhh Kayyy. Here we go. This is basically your problem.' / Olivia took a few steps back as the bottom-cleavage started wriggling out towards her. Connor the counter-surveillance expert pulled himself awkwardly to his knees, […]

   • 2014, Bridgett M. Davis, Into the Go-Slow, New York, N.Y.: The Feminist Press at the City University of New York, →ISBN:

     Brenda lifted the top off a shoebox and dug beneath the tissue paper, unearthing a two-toned, turquoise-and-cream, high-heeled pump. "This is one of my favorites," she said, balancing it in the palm of her hand. "I love shoes that show toe cleavage." / "Toe cleavage?" / Brenda kicked off a leather sandal, slipped her foot into the pump, and pointed to the baseline of her toes peeking through. "That's toe cleavage!"

4. (biology) The repeated division of a cell into daughter cells after mitosis. [from 19th c.]
   • 2008 spring, Dierdre Colleen Lyons, “Mechanisms Controlling the Asymmetric Second Cleavage”, in Mechanisms Controlling the Asymmetric Second Cleavage in the Helobdella Embryo (unpublished Ph.D. in Molecular and Cell Biology dissertation), Berkeley, Calif.: University of California, Berkeley, →OCLC, page 16:

     [C]itellate annelids (leeches + oligochaetes) provide solid ground for comparative analyses, because they form a monophyletic group within the paraphyletic polychaetes […]. […] The unequal cleavage of the zygote followed by the unequal cleavage of the CD cell is critical for D-quadrant specification since the cytoplasmic determinants present in teloplasm are segregated to the larger CD cell at first asymmetric cleavage and then to the larger D cell at the second asymmetric cleavage […].

5. (chemistry) The splitting of a large molecule into smaller ones.
   • 2006, E. K. Marasco, K. Vay, C. Schmidt-Dannert, “Identification of Carotenoid Cleavage Oxygenases from Nostoc sp. PCC7120 with Different Cleavage Activities”, in Journal of Biological Chemistry, volume 42, abstract, page 281:

     Carotenoid cleavage oxygenases (CCOs) are a class of enzymes that oxidatively cleave carotenoids into apocarotenoids. Carotenoid cleavage oxygenases have been identified in plants and animals and produce a wide range of cleavage products. […] Two of the three enzymes showed cleavage of β, β-carotene at the 9,10 and 15,15' position, respectively.

6. (mineralogy) The tendency of a crystal to split along specific planes. [from 19th c.]
   • 1982, Alan Holden, Phylis Morrison, “Cleaving and Gliding Crystals”, in Crystals and Crystal Growing, Cambridge, Mass., London: MIT Press, →ISBN, page 202:

     Notice that cleavage has nothing to do with imperfections in the crystal. Indeed, if you try cleaving an imperfect crystal, you may find that it cannot be cleaved as well as a perfect one. The cleavage is the result of the orderliness of the atomic arrangement. No wonder imperfections, which disturb the orderliness, disturb the cleavage as well. You will also note that the cleavage directions are obedient to the symmetry of the crystal.

7. (politics) The division of voters into voting blocs.
   • 2011, Scot Schraufnagel, “Voting bloc”, in Historical Dictionary of the U.S. Congress, Lanham, Md.: Scarecrow Press, →ISBN, page 235:

     A voting bloc in Congress can represent a long-standing alliance or can be created anew as a result of the increased saliency of a particular issue, such as war or a severe economic downturn. A division between voting blocs is called a cleavage and because voting blocs are impermanent, dominant cleavages are always changing.

• (separation between breasts): intermammary sulcus

• cleave
• cleft

• décolletage
• spathic