WordNet (r) 3.0 (2006):

reflectivity
    n 1: the fraction of radiant energy that is reflected from a
         surface [syn: coefficient of reflection, reflection
         factor, reflectance, reflectivity]
    2: the ability to reflect beams or rays [syn: reflection,
       reflexion, reflectivity]
    3: the capability of quiet thought or contemplation [syn:
       reflectiveness, reflectivity]