(n.) Green vitriol, or sulphate of iron; a green crystalline substance, of an astringent taste, used in making ink, in dyeing black, as a tonic in medicine, etc. It is made on a large scale by the oxidation of iron pyrites. Called also ferrous sulphate.
COPPERAS
Meaning of COPPERAS in English
Webster's English dictionary. Английский словарь Webster. 2012