noun

1. a pale-yellow, nonmetallic chemical element found in crystalline or amorphous form: it burns with a blue flame and a stifling odor and is used in vulcanizing rubber and in making matches, paper, gunpowder, insecticides, sulfuric acid, etc.: symbol, S; at. no., 16
2. any of numerous small to medium-sized butterflies (family Pieridae) having yellow or orange wings with dark borders
   in full sulfur butterfly
3. yellow with a greenish tinge: often sulfur yellow

Etymology: ME sulphur < L

transitive verb