re·flec·tiv·i·ty 
(rē′flĕk-tĭvĭ-tē)
(rē′flĕk-tĭvĭ-tē)n. pl. re·flec·tiv·i·ties
1. The quality of being reflective.
2. The ability to reflect.
3. Physics The ratio of the energy of a wave reflected from a surface to the energy possessed by the wave striking the surface.