Vergency
Pronunciation : Ver"gen*cy
Part of Speech : n.
Definition : 1. The act of verging or approaching; tendency; approach. [R.]
2. (Opt.)
Defn: The reciprocal of the focal distance of a lens, used as measure of the divergence or convergence of a pencil of rays. [R.] Humphrey Lloyd.
Source : Webster's Unabridged Dictionary, 1913