sulfur

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A pale yellow nonmetallic element occurring widely in nature in several free, allotropic and crystal forms and combined in numerous sulfates and sulfides. It is used in black gunpowder, rubber vulcanization, the manufacture of insecticides and pharmaceuticals, and in the preparation of sulfur compounds such as hydrogen sulfide and sulfuric acid. Atomic number 16; atomic weight 32.066; melting point 115.21°C; boiling point 444.61°C; specific gravity at 20°C (rhombic) 2.07, (monoclinic) 2.00; valence 2, 4, 6. cross-reference: Periodic Table.
• noun Any of various butterflies of the subfamily Coliadinae of the family Pieridae, having yellow or orange wings often marked with black.
• transitive verb To treat with sulfur or a compound of sulfur.

from The Century Dictionary.

• An amended (restored) spelling of sulphur (Latin sulfur).

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun uncountable A chemical element (symbol S) with an atomic number of 16.
• noun countable, uncountable A yellowish green colour, like that of sulfur.
• adjective Of a yellowish green colour, like that of sulfur.
• verb transitive To treat with sulfur, or a sulfur compound, especially to preserve or to counter agricultural pests.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb treat with sulphur in order to preserve
• noun an abundant tasteless odorless multivalent nonmetallic element; best known in yellow crystals; occurs in many sulphide and sulphate minerals and even in native form (especially in volcanic regions)