a unit of prismatic deviation, in which the number one represents a prism that deflects a beam of light a distance of one centimeter on a plane placed normal to the initial direction of the beam and one meter away from the prism.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
The unit measuring the deflection of light passing through a prism equal to a deflection of 1 centimeter at a distance of 1 meter.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.