English

Noun

vergency ‎(plural vergencies)

1. The act of verging or approaching; tendency.
2. The reciprocal of the focal distance of a lens, used as a measure of the divergence or convergence of a pencil of rays.
   • 1863, The Civil Engineer and Architect's Journal

     When, by the pencil becoming oblique to the surface, the vergency produced on the pencil becomes changed, the primary and secondary focal points, V and H, separate […]