cardinal point

cardinal point

[′kärd·nəl ¦pȯint]

(geodesy)

Any of the four principal directions: north, east, south, or west of a compass.

(optics)

Any one of six points in an optical system, namely, the two principal points, two nodal points, and two focal points. Also known as Gauss point.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.