n. A hydrate whose solid contains seven molecules of water of crystallization per molecule, or per unit cell
The Century Dictionary and Cyclopedia
n. In chem., a compound containing seven molecules of water, as common copperas in crystals, or ferrous sulphate heptahydrate (FeSO4.7H2O).
Word Usage
"[46] Green vitriol, ferrous sulphate heptahydrate, a compound of iron, sulphur, and oxygen, crystallised with seven molecules of water, represented by the formula FeSO4."