the GNU version of the Collaborative International Dictionary of English
n. A sulphate in which but half the hydrogen of the acid is replaced by a positive element or radical, thus making the proportion of the acid to the positive or basic portion twice what it is in the normal sulphates; an acid sulphate.
The Century Dictionary and Cyclopedia
n. In chem., a salt of sulphuric acid, in which one half of the hydrogen of the acid is replaced by a metal.
Word Usage
"Sodium bisulphate is currently the best choice to poison crown-of-thorns with, since it eventually breaks down in seawater."