1. A screening against light or heat.
2. The lines or other marks used to fill in outlines of a sketch, engraving, or painting to represent gradations of color or darkness.
3. A small variation, gradation, or difference.

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.