refractivity
/ˌriːfrækˈtɪvəti/
noun
- The ability of a substance (such as glass, water, or air) to bend light as it passes through it.
- Scientists measured the refractivity of the new optical lens material.
- The high refractivity of diamond gives it its brilliant sparkle.
- Changes in air temperature affect the refractivity of the atmosphere, causing mirages.