carbon (Noun) — An abundant nonmetallic tetravalent element occurring in three allotropic forms: amorphous carbon and graphite and diamond; occurs in all organic compounds.
carbon (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.
carbon (Noun) — A copy made with carbon paper.
carbon (Noun) — Fossil fuel use, regarded as a contributor to global warming; the amount of carbon dioxide contributed to the atmosphere by a process or activity, or the amount of carbon in the carbon dioxide released.