Prussian blue

noun

1

: any of numerous blue iron pigments formerly regarded as ferric ferrocyanide

2

: a dark blue crystalline hydrated ferric ferrocyanide Fe₄[Fe(CN)₆]₃·xH₂O used as a test for ferric iron

3

: a greenish blue

Examples of Prussian blue in a Sentence

Recent Examples on the Web

The delivery of cytokines can stimulate the white blood cell production that is damaged by exposure; treatment with potassium iodide or Prussian blue can help eliminate radioactive particles from the body; and proper washing can prevent skin burns that might take days to show up. — New Atlas, 28 Jan. 2026

Maybe Prussian blue is a little easier to wear than orange, red and black, the colors of the German flag, but the piece de resistance was the tiara. — Monique Jessen, PEOPLE, 19 Dec. 2025

This year, paint manufacturers anticipate that deeper, more complex blues, such as cerulean and Prussian blue, will trend. — Cyndy Aldred, Better Homes & Gardens, 6 Jan. 2025

As the legend goes, Prussian blue was created by accident when a batch of carmine was contaminated with blood. — John Cumbers, Forbes, 6 May 2023

Potassium iodide pills would likely not be recommended for that kind of radiation exposure, the CDC says, but a treatment based on a drug called Prussian blue could be used. — Trevor Hughes, USA TODAY, 8 Dec. 2022

Only after that do figures emerge, pulled out from the river of time and foregrounded in colors of yellow, turquoise, Pepto pink and Prussian blue. — Dallas News, 28 Sep. 2022

Word History

Etymology

Prussia, Germany

First Known Use

1724, in the meaning defined at sense 1

Rhymes for Prussian blue

• accrue
• ado
• ainu
• aircrew
• airscrew
• anew
• askew
• baboo
• babu
• bamboo
• beaucoup
• bijou

Medical Definition

Prussian blue

noun

Prus·​sian blue ˈprəsh-ən-ˈblü 

1

: any of numerous blue iron pigments formerly regarded as the ferric salt of ferrocyanide

2

: a dark blue crystalline hydrated compound Fe₄[Fe(CN)₆]₃·xH₂O that is a ferrocyanide of iron and is used as a test for ferric iron

called also ferric ferrocyanide