Prussian blue

noun

Prus·​sian blue ˈprə-shən- 

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

Word History

Etymology

Prussia, Germany

First Known Use

1724, in the meaning defined at sense 1

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