Ferricyanide n. (Chem.) One of a complex series of double cyanides of ferric iron and some other base. Potassium ferricyanide (Chem.), red prussiate of potash; a dark, red, crystalline salt, K6(CN)12Fe2, consisting of the double cyanide of potassium and ferric iron. From it is derived the ferrous ferricyanate, Turnbull's blue.