Definition of "angle of incidence" []

• The angle formed by a ray incident on a surface and a perpendicular to the surface at the point of incidence. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The angle of incidence is understood as defined by Alhazen and Vitellio"