polysulfides

Compounds R–[S]_n–R , with a chain of sulfur atoms ( $n ≥ 2$ ) and R ≠ H. Some chemists exclude disulfides, RS₂R , from the class polysulfides.

Source:

PAC, 1995, 67, 1307 (Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)) on page 1360