Cŏp'per-as, n.

n. [It. copparosa, Sp. & Pg. caparrosa, Fr. couperose, L. Lat. cuprosa, cuperosa, coporosa, O. Ger. koper-roose, from Lat. cuprirosa, equivalent to Gr. χάλκανθος, i. e., copper-flower, D. koperrood, i. e., copper-red.] Sulphate of iron, or green vitriol; a salt of a green color, and styptic, astringent taste.

☞ It is much used in dyeing black, and in making ink, and in medicine as a tonic. The copperas of commerce is usually made by the decomposition of iron pyrites. The term copperas was formerly synonymous with vitriol, and included the green, blue, and white vitriols, or the sulphates of iron, copper, and zinc. Dana.