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Copperas

Copperas Cop"per*as, n. [OE. coperose, F. couperose, fr. (assumed?) L. cuprirosa, equiv. to G. cha`lkanqos, i. e. copper flower, vitriol. See Copper and Rose.] 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}. [1913 Webster]

Note: The term copperas was formerly synonymous with vitriol, and included the green, blue, and white vitriols, or the sulphates of iron, copper, and zinc. [1913 Webster]