from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The ratio of the speed of light in a vacuum to the speed of light in a medium under consideration. Also called refractive index.
from the GNU version of the Collaborative International Dictionary of English
- n. the number which expresses the ratio of the sine of the angle of incidence to the sine of the angle of refraction. Thus the index of refraction for sulphur is 2, because, when light passes out of air into sulphur, the sine of the angle of incidence is double the sine of the angle of refraction.
- n. See under Index.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. the ratio of the velocity of light in a vacuum to that in a medium
Sorry, no etymologies found.