error of perpendicularity

error of perpendicularity

[′er·ər əv ‚pər·pən‚dik·yə′lar·əd·ē]
(navigation)
That error in the reading of a marine sextant due to nonperpendicularity of the index mirror to the frame.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.