vergency

Etymology
+, cf. New Latin (16th century), French  (18th century) and later English  (20th century).

Noun

 * 1)  The act of verging or approaching; tendency, inclination towards something.
 * 2) ** s.v. : "vergency, incline"
 * 3) ** "the Earth is moved about the Sun by its Inclination and Vergency towards it"
 * 4) * 1721 Nathan Bailey, An Universal Etymological English Dictionary, E. Bell, London.
 * 5) ** "VERGENCY [of, L.] a bending or declining away, from or to, inclining."
 * 6) The reciprocal of the focal distance of a lens, used as a measure of the divergence or convergence of a pencil of rays.
 * 1) ** "VERGENCY [of, L.] a bending or declining away, from or to, inclining."
 * 2) The reciprocal of the focal distance of a lens, used as a measure of the divergence or convergence of a pencil of rays.