Webster’s Revised Unabridged Dictionary · 1913
Prussic
Prus′sic (prŭs′sĭk or prṳs′sĭk; 277), a. [Cf. F. prussique.] (Old Chem.) designating the acid now called hydrocyanic acid, but formerly called prussic acid, because Prussian blue is derived from it or its compounds. See Hydrocyanic.