1) Bending 2) Deflection 3) Deflexion 4) Refractivity 1) Refractivity 
• (n.) The quality or condition of being refractive.
A measure of how much a sheet of paper deflects the light that hits it. The more light a sheet deflects, the greater its refractive- ness, allowing a printed image to be more brilliant and detailed. see also brightness, whiteness.
Re·fract'ive·ness noun The quality or condition of being refractive.