either of two points on the axis of a lens or other optical system, determined by extending an incident oblique ray and the corresponding refracted ray to the axis for the pair of rays that are parallel outside the optical system.
Read more in this article about some frequently asked questions and fun facts related to our definitions.
Moot Point vs. Mute Point
You may have heard coworkers or acquaintances refer to an inconsequential or irrelevant point as a moot point, or maybe you’ve heard mute point instead. Fans of the TV show Friends may have heard a third variation: moo point (because, according to Joey, a cow’s opinion doesn’t matter). But which expression is correct, and what exactly does it mean? The correct phrase is moot point. …
Origin of nodal point
First recorded in 1835–45
Also called node.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
One of the two points in a compound optical system, located so that a light ray directed through the first point will leave the system through the second point, parallel to its original direction.axial point
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.