Prussian blue

American  

noun

1. a moderate to deep greenish blue.

2. one of the iron blues, a dark-blue, crystalline, water-insoluble pigment, Fe 4 [Fe(CN) 6 ] 3 , produced by reacting ferrocyanic acid or a ferrocyanide with a ferric compound: used in painting, fabric printing, and laundry bluing.

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Prussian blue British  

noun

1. any of a number of blue pigments containing ferrocyanide or ferricyanide complexes

2. 1. the blue or deep greenish-blue colour of this pigment

   2. ( as adjective )

      a Prussian-blue carpet

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Etymology

Origin of Prussian blue

1715–25; translation of French bleu de Prusse, so called because it was discovered and first reported in Berlin, capital of Prussia

Example Sentences

I imagined a vitrine of the pigments used to achieve those “Gainsborough blues”—indigo, Prussian blue, ultramarine, azurite.

From The Wall Street Journal • Mar. 4, 2026

You know the print: swoops of Prussian blue water topped with white foam curling like fingers above the abyss, Mount Fuji in the back.

From Seattle Times • Sep. 7, 2023

Although I'm much more accustomed to sticking to neutrals, I've learned I shouldn't fear an emerald green or Prussian blue.

From Salon • Jul. 31, 2022

"There were just four stamps printed, and then there was a mistake and they printed several sheets in the wrong colour - Prussian blue - and they are very rare and very expensive."

From BBC • May 31, 2022

He makes adjustments to the flood of Prussian blue paper himself, responding to her arrangements, surrounding replicas of ancient Egyptian temples with columns of curving bookshelves.

From "The Night Circus" by Erin Morgenstern