involution

From Latin involūtiō, from involvō.

• IPA^(key): /ɪnvəˈluːʃən/

• Audio (Southern England):

  (file)

• Rhymes: -uːʃən

involution (countable and uncountable, plural involutions)

1. Entanglement; a spiralling inwards; intricacy.
   • 1938, Xavier Herbert, chapter V, in Capricornia‎^[1], page 74:

     […] usually his attention was diverted from her feet by her shrieks of laughter and the astounding involutions of her huge brown-yellow frame.

   • 1968, Anthony Burgess, “Enderby Outside”, in The Complete Enderby, published 2002, page 302:

     ‘Gomez,’ said the mortician, ‘is an expert only on the involutions of his own rectum.’

2. A complicated grammatical construction.
   • 1917, James Huneker, Unicorns, New York: Scribner, Chapter 11 “Style and Rhythm in English Prose,” p. 129,^[2]

     Walter Pater’s essay on Style is honeycombed with involutions and preciosity.

4. (mathematics) An endofunction whose square is equal to the identity function; a function equal to its inverse.

   Hyponyms: complex conjugation, complementation

   • 1996, Alfred J. Menezesm, Paul C. van Oorschot, Scott A. Vanstone, Handbook of Applied Cryptography, CRC Press, page 10:

     Involutions have the property that they are their own inverses.

6. (medicine) The shrinking of an organ (such as the uterus) to a former size.
7. (physiology) The regressive changes in the body occurring with old age.

   Coordinate terms: aging, ageing

8. (mathematics, obsolete) A power: the result of raising one number to the power of another.
10. (economics, social sciences, of a society or nation) A cessation of development or progress involving intense inner competition.
11. (neologism) A state of increased competition for limited resources, requiring great effort to stay ahead.
12. (biology) The migration of a cell layer inward, sliding over an outer layer of cells. It occurs at gastrulation during embryogenesis.

• involutional
• involutionary
• involve

• dual
• selfdual