vergence

Etymology
From, synonym of earlier (1660s) (the equivalent of ). Coined as a technical term in ophthalmology, as a hyperonym of and, in 1902. The sense of the numeric quantity in geometric optics was introduced, from use of the term in physiological optics, in the 1920s.

Noun

 * 1)  The simultaneous turning of both eyes when focusing.
 * 2)  A measure of convergence or divergence of rays.
 * 3) ** "a special vertex trial case computed for an object vergence of 4.00."
 * 4) * 1947 Benjamin King Johnson, Optics and Optical Instruments: An Introduction with Special Reference to Practical Applications, Courier Corporation (1960 [1947]), p. 152.
 * 5) ** "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"
 * 6)  The direction of the overturned component of an asymmetric fold.
 * 1)  The direction of the overturned component of an asymmetric fold.

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

Noun

 * 1)   the quality of being inclined or tending towards something
 * 2) * 1738 Philippe Hecquet, La medecine naturelle chez Guillaume Cavelier, p. 646.
 * 3) ** "il [Hippocrate] recommande de bien s'assurer de la vergence des humeurs, cest-a-dire, d'où elles partent & vers où elles tendent."
 * 4) * 1740 Philippe Hecquet, La medecine, la chirurgie, et la pharmacie des pauvres, t. 2, chez la Veuve Alix, p. 354.
 * 5) ** "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."
 * , the simultaneous turning of both eyes when focusing.
 * , a measure of convergence or divergence of rays.