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