Definition of "iron blue" [iron blue]

• Any of various light-resistant and heat-resistant, semitransparent blue pigments of powerful tinctorial strength, used chiefly in permanent industrial finishes, printing inks, and artists' colors. Also called Prussian blue. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.