What is Sulfur?

Sulfur definition and meaning on Dictionary terms:
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