salt or other derivative of hydrogen sulfide or organic compound having the structure RSR (R ≠ H)

A sulphide (sulfide in US English) is an anion of sulphur in its lowest oxidation number of -2. Sulphide is also a term for thioethers, a common type of compound which are known for their bad odours (example: H2S = hydrogen sulphide).

The dianion S2- exists only in strongly alkaline aqueous solutions.