reflectance definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
Physics the ratio of the amount of electromagnetic radiation, usually light, reflected from a surface to the amount originally striking the surface
reflectance definition by American Heritage Dictionary
The ratio of the total amount of radiation, as of light, reflected by a surface to the total amount of radiation incident on the surface.