vergence

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English

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Etymology

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From verge (tend, incline, from Latin vergere) +‎ -ence, synonym of earlier (1660s) vergency (the equivalent of French vergence). Coined as a technical term in ophthalmology, as a hyperonym of convergence and divergence, in 1902. The sense of the numeric quantity in geometric optics was introduced, from use of the term in physiological optics, in the 1920s.

Pronunciation

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Noun

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vergence (countable and uncountable, plural vergences)

  1. (physiology) The simultaneous turning of both eyes when focusing. [1902]
  2. (optics) A measure of convergence or divergence of rays. [c. 1920]
    • 1921, The Optician and Scientific Instrument Maker, volume 62, page 1:
      • "a special vertex trial case computed for an object vergence of 4.00."
    • 1947 Benjamin King Johnson, Optics and Optical Instruments: An Introduction with Special Reference to Practical Applications, Courier Corporation (1960 [1947]), p. 152.
      • "Ample movement between the source and condenser should be available in order to allow for a variation in the vergence of the light leaving the condenser"
  3. (geology) The direction of the overturned component of an asymmetric fold.

French

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Etymology

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1738, glosses New Latin vergentia in the Latin translations of Hippocrates (16th century).

Pronunciation

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Noun

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vergence f (plural vergences)

  1. (dated, medicine) the quality of being inclined or tending towards something [1738]
    • 1738 Philippe Hecquet, La medecine naturelle chez Guillaume Cavelier, p. 646.
      • "il [Hippocrate] recommande de bien s'assurer de la vergence des humeurs, cest-a-dire, d'où elles partent & vers où elles tendent."
    • 1740 Philippe Hecquet, La medecine, la chirurgie, et la pharmacie des pauvres, t. 2, chez la Veuve Alix, p. 354.
      • "C'est que, suivant le langage d'Hippocrate, l'on ne sçauroit avoir trop d'égard à la vergence des humeurs en fait de purgation, quò vergunt humores eò ducendi."
  2. (physiology) vergence, the simultaneous turning of both eyes when focusing.
  3. (optics) vergence, a measure of convergence or divergence of rays. [c. 1920]
    • 1924, M. Dufour, “Le rôle de la vergence en dioptrique”, in Annales d'oculistique, Paris:

Further reading

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