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chemistry : a yellow chemical element that has a strong, unpleasant odor when it is burned and that is used in making paper, gunpowder, medicine, etc.
Full Definition of SULFUR
: a nonmetallic element that occurs either free or combined especially in sulfides and sulfates, is a constituent of proteins, exists in several allotropic forms including yellow orthorhombic crystals, resembles oxygen chemically but is less active and more acidic, and is used especially in the chemical and paper industries, in rubber vulcanization, and in medicine for treating skin diseases — see element table
The spelling sulfur predominates in United States technical usage, while both sulfur and sulphur are common in general usage. British usage tends to favor sulphur for all applications. The same pattern is seen in most of the words derived from sulfur.
Middle English sulphur brimstone, from Latin sulpur, sulphur, sulfur
First Known Use: 14th century
Sulfur crystals from Sicily (greatly enlarged)—Courtesy of the Illinois State Museum; photograph, John H. Gerard
Nonmetallic chemical element, chemical symbol S, atomic number 16. It is very reactive but occurs native in deposits, as well as combined in various ores (e.g., pyrite, galena, cinnabar); in coal, petroleum, and natural gas; and in the water in sulfur springs. Sulfur is the third most abundant constituent of minerals and one of the four most important basic chemical commodities. Pure sulfur, a tasteless, odourless, brittle yellow solid, occurs in several crystalline and amorphous allotropes, including brimstone and flowers of sulfur. It combines, with valence 2, 4, or 6, with nearly all other elements. Its most familiar compound is hydrogen sulfide, a poisonous gas that smells like rotten eggs. All metals except gold and platinum form sulfides, and many ores are sulfides. The oxides are sulfur dioxide and sulfur trioxide, which when dissolved in water make sulfurous acid and sulfuric acid, respectively. Several sulfur compounds with halogen elements are industrially important. Sodium sulfite (NaSO) is a reducing agent used to pulp paper and in photography. Organic compounds with sulfur include several amino acids, the sulfa drugs, and many insecticides, solvents, and substances used in making rubber and rayon.