Sulfur

noun
1.
Also, especially British, sulphur. Chemistry. a nonmetallic element that exists in several forms, the ordinary one being a yellow rhombic crystalline solid, and that burns with a blue flame and a suffocating odor: used especially in making gunpowder and matches, in medicine, in vulcanizing rubber, etc. Symbol: S; atomic weight: 32.064; atomic number: 16; specific gravity: 2.07 at 20° C.
2.
sulphur (def 2).
noun
1.
the US preferred spelling of sulphur

sulfur sul·fur or sul·phur (sŭl’fər)
n.
Symbol S
A yellow nonmetallic element occurring widely in nature in several free and combined allotropic forms and used in the manufacture of pharmaceuticals and many sulfur compounds, especially sulfuric acid. Atomic number 16; atomic weight 32.066; melting point (rhombic) 112.8°C; (monoclinic) 119.0°C; boiling point 444.6°C; specific gravity (rhombic) 2.07; (monoclinic) 1.957; valence 2, 4, 6.
sulfur also sulphur
(sŭl’fər)
Symbol S
A pale-yellow, brittle nonmetallic element that occurs widely in nature, especially in volcanic deposits, minerals, natural gas, and petroleum. It is used to make gunpowder and fertilizer, to vulcanize rubber, and to produce sulfuric acid. Atomic number 16; atomic weight 32.066; melting point (rhombic) 112.8°C; (monoclinic) 119.0°C; boiling point 444.6°C; specific gravity (rhombic) 2.07; (monoclinic) 1.957; valence 2, 4, 6. See Periodic Table.