1. The deflection of a wave, such as a light or sound wave, when it passes obliquely from one medium into another having a different index of refraction.
2. Astronomy The apparent change in position of a celestial object caused by the bending of light rays as they enter Earth's atmosphere.
a. The ability of the eye to bend light so that an image is focused on the retina.
b. Determination of this ability in an eye.
re·fraction·al, re·fractive adj.
re·fractive·ness, re′frac·tivi·ty (rē′frăk-tĭvĭ-tē) n.
(click for a larger image)refraction
refraction of light
i: angle of incidence
r: angle of refraction
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.