1. Symbol C 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. See Periodic Table.
2. A carbon-containing gas, notably carbon dioxide, or a collection of such gases, especially when considered as a contributor to the greenhouse effect: plans for capturing and sequestering carbon produced by power plants.
a. A sheet of carbon paper.
b. A carbon copy.
a. Either of two rods through which current flows to form an arc, as in lighting or welding.
b. A carbonaceous electrode in an electric cell.
[French carbone, from Latin carbō, carbōn-, a coal, charcoal; see ker-3 in the Appendix of Indo-European roots.]
carbon·ous (-bə-nəs) adj.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.