1. a column or pin on a sundial, etc. that casts a shadow indicating the time of day
2. the part of a parallelogram remaining after a similar, smaller parallelogram has
been taken from one of its corners
Webster’s New World College Dictionary, Fourth Edition, compiled by the
editors of Webster’s New World Dictionaries. Copyright © 2010 by Houghton
Mifflin Harcourt. Published by Houghton Mifflin Harcourt. All rights reserved.
Word origin of 'gnomon'
L < Gr gnōmōn
, one who knows or examines, index of a sundial < base of gignōskein
, to know