Definition of refractiveness in US English:

refractiveness

noun

  • The state or property of being refractive; (Medicine and Biology) resistance to infection, a parasite, etc.

Origin

Late 17th century; earliest use found in Robert Hooke (1635–1703), natural philosopher. From refractive + -ness.

Pronunciation

refractiveness

/rɪˈfraktɪvnɪs/