carbon

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

• noun An abundant nonmetallic element that occurs in many inorganic and in all organic compounds, exists freely in amorphous, graphite, and diamond forms and as a constituent of coal, limestone, and petroleum, and is capable of chemical self-bonding to form an enormous number of chemically, biologically, and commercially important molecules. Other significant allotropes include fullerenes and nanotubes. Atomic number 6; atomic weight 12.011; sublimation point 3,825°C; triple point 4,489°C; specific gravity of amorphous carbon 1.8 to 2.1, of diamond 3.15 to 3.53, of graphite 1.9 to 2.3; valence 2, 3, 4. cross-reference: Periodic Table.
• noun A carbon-containing gas, notably carbon dioxide, or a collection of such gases, especially when considered as a contributor to the greenhouse effect.
• noun A sheet of carbon paper.
• noun A carbon copy.
• noun Either of two rods through which current flows to form an arc, as in lighting or welding.
• noun A carbonaceous electrode in an electric cell.

from The Century Dictionary.

• To put carbons in (an arc lamp).
• noun Chemical symbol, C; atomic weight, 11.97. An element found in nature in two distinct forms: the diamond, which is extremely hard, of high specific gravity (3.5), usually colorless and transparent, with brilliant adamantine luster, and crystallizes in octahedrons; and graphite, which is very soft, of low specific gravity , black and opaque, with metallic luster, and crystallizes in hexagonal plates. See diamond and graphite.
• noun The form of the diamond generally called carbonado; the black diamond.
• noun In electric lighting, a carbon-point (see below).

from the GNU version of the Collaborative International Dictionary of English.

• noun (Chem.) 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.
• noun (Elec.) 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.
• noun a sheet of carbon paper.
• noun a carbon copy.
• noun (Chem.) those compounds consisting largely of carbon, commonly produced by animals and plants, and hence called organic compounds, though their synthesis may be effected in many cases in the laboratory.
• noun originally, a copy of a document made by use of a carbon paper, but now used generally to refer to any copy of a document made by a mechanical process, such as xerographic copying.
• noun (Chem.) See under Carbonic.
• noun (Elec.) an extremely brilliant electric light produced by passing a galvanic current through two carbon points kept constantly with their apexes neary in contact.
• noun (Elec.) a small cylinder or bit of gas carbon moved forward by clockwork so that, as it is burned away by the electric current, it shall constantly maintain its proper relation to the opposing point.
• noun a thin type of paper coated with a dark-colored waxy substance which can be transferred to another sheet of paper underneath it by pressing on the carbon paper. It is used by placing a sheet between two sheets of ordinary writing paper, and then writing or typing on the top sheet, by which process a copy of the writing or typing is transferred to the second sheet below, making a copy without the need for writing or typing a second time. Multiple sheets may be used, with a carbon paper placed above each plain paper to which an impression is to be transferred. In 1997 such paper was still used, particularly to make multiple copies of filled-in purchase invoice forms, but in most applications this technique has been superseded by the more faithful xerographic reproduction and computerized printing processes.
• noun paper coated with gelatine and pigment, used in the autotype process of photography.
• noun a compact variety of carbon obtained as an incrustation on the interior of gas retorts, and used for the manufacture of the carbon rods of pencils for the voltaic, arc, and for the plates of voltaic batteries, etc.

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

• noun uncountable The chemical element (symbol C) with an atomic number of 6.
• noun countable, informal A sheet of carbon paper.
• noun countable, informal A carbon copy.
• noun A fossil fuel that is made of impure carbon such as coal or charcoal.
• noun ecology, uncountable Carbon dioxide, in the context of global warming and climate change.

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

• noun a copy made with carbon paper
• noun an abundant nonmetallic tetravalent element occurring in three allotropic forms: amorphous carbon and graphite and diamond; occurs in all organic compounds
• noun 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