Sulphydrate \Sul*phy"drate\, n. (Chem.) A compound, analogous to a hydrate, regarded as a salt of sulphydric acid, or as a derivative of hydrogen sulphide in which one half of the hydrogen is replaced by a base (as potassium sulphydrate, KSH), or as a hydrate in which the oxygen has been wholly or partially replaced by sulphur.

Source: Webster's Revised Unabridged Dictionary (1913)