Wiktionary
disulfur
n. (context inorganic chemistry in combination English) Two atoms of sulfur in a compound.
Wikipedia
Disulfur
Disulfur is the diatomic molecule with the formula S. It is analogous to the dioxygen molecule but rarely occurs at room temperature. This violet gas is commonly generated by heating sulfur above 720 °C and comprises 99% of the vapor at low pressure (1 mm Hg) at 530 °C. S is one of the minor components of the atmosphere of Io, which is predominantly composed of SO. Diatomic molecules are common containing C, O, N, and F, but for heavier elements they are often only stable at high temperatures.