Meaning of Prussian blue

Prus'sian blue'

Pronunciation: [key]
  1. a moderate to deep greenish blue.
  2. one of the iron blues, a dark-blue, crystalline, water-insoluble pigment, Fe[Fe(CN)], produced by reacting ferrocyanic acid or a ferrocyanide with a ferric compound: used in painting, fabric printing, and laundry bluing.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.