re·frac·tion (rĭ-frăk'shən)
n.

1. The turning or bending of any wave, such as a light or sound wave, when it passes from one medium into another of different optical density.
2. Astronomy. The apparent change in position of celestial objects caused by the bending of light rays entering Earth's atmosphere.
3. Medicine.
   1. The ability of the eye to bend light so that an image is focused on the retina.
   2. Determination of the refractive characteristics of the eye.

refractional re·frac'tion·al or re·frac'tive adj.
refractively re·frac'tive·ly adv.
refractiveness re·frac'tive·ness or re'frac·tiv'i·ty (rē'frăk-tĭv'ĭ-tē) n.

---

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.

---