ˈkäp(ə)rəs noun
( -es )
Etymology: alteration of Middle English coperose, from Middle French coperose, couperose, from (assumed) Vulgar Latin cuprirosa, from Late Latin cupri- (from cuprum copper) + Latin rosa rose — more at rose
1. obsolete : vitriol 1a
2. : green ferrous sulfate heptahydrate
3. archaic : a green obtained by use of copperas in dyeing — used attributively especially of trousers