principal point

noun Optics.
the point where a principal plane intersects the axis.

1695–1705 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
Cite This Source Link To principal point
American Heritage
Medical Dictionary

principal point n.
One of the two points in an optical system where the axis is cut by the two principal planes. Lines drawn from these to corresponding points on the object and the image will be parallel.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Cite This Source
Example sentences
One principal point of difference, looking ahead, is the cost of state pensions.
The entire case below and the principal point in this appeal concern the
  attorney-client agreement.
It serves as the principal point of contact for economic development issues and
The contractor shall designate a principal point of contact for technical
Copyright © 2014, LLC. All rights reserved.
  • Please Login or Sign Up to use the Recent Searches feature