1. An insoluble dark blue pigment and dye, ferric ferrocyanide or one of its modifications.
2. See iron blue.
3. A moderate to strong blue or deep greenish blue.
[From its having been discovered by an 18th-century color-maker in Berlin (then in Prussia).]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.