%convergency%

{ , n. [ Cf. F. convergence. ] 1. The condition or quality of converging; tendency to one point; the occurrence of two or more things coming together. [ 1913 Webster ]

2. (Math.) the approach of an infinite series to a finite limit.
Syn. -- convergency. [ WordNet 1.5 ]

3. a representation of common ground between theories or phenomena.
Syn. -- overlap, intersection. [ WordNet 1.5 ]

4. the act of converging (coming closer).
Syn. -- converging, convergency. [ WordNet 1.5 ]

5. (Biol.) a similarity of form or function in two or more organisms caused by evolutionary adaptations to a similarity in the environment, rather than to a common heredity. [ PJC ]

The convergence or divergence of the rays falling on the pupil. Berkeley. [ 1913 Webster ]