1. an abundant nonmetallic tetravalent element occurring in three allotropic forms: amorphous carbon and graphite and diamond; occurs in all organic compounds
2. a thin paper coated on one side with a dark waxy substance (often containing carbon); used to transfer characters from the original to an under sheet of paper
3. a copy made with carbon paper
4. An elementary substance, not metallic in its nature, which is present in all organic compounds. Atomic weight 11.97. Symbol C. it is combustible, and forms the base of lampblack and charcoal, and enters largely into mineral coals. In its pure crystallized state it constitutes the diamond, the hardest of known substances, occuring in monometric crystals like the octahedron, etc. Another modification is graphite, or blacklead, and in this it is soft, and occurs in hexagonal prisms or tables. When united with oxygen it forms carbon dioxide, commonly called carbonic acid, or carbonic oxide, according to the proportions of the oxygen; when united with hydrogen, it forms various compounds called hydrocarbons. Compare Diamond, and Graphite.
5. A carbon rod or pencil used in an arc lamp; also, a plate or piece of carbon used as one of the elements of a voltaic battery.