RhymeZone: disulfide definitions

Definitions of disulfide:

noun: (organic chemistry) A functional group with two sulfur atoms bonded to one another, described by the following formula: R–S–S–R'.
noun: (inorganic chemistry) The anion ⁻S–S⁻.
noun: (inorganic chemistry) A binary compound of sulfur and another element in the ratio 2:1 (formula XS₂).

(Definitions from Wiktionary)