car tyre(A rubber ring placed over the rim of a wheel of a road vehicle to provide traction and reduce road shocks, especially a hollow inflated ring consisting of a reinforced outer casing enclosing an inner tube)
carbon(A nonmetallic element existing in the three crystalline forms: graphite, diamond and buckminsterfullerene: occurring in carbon dioxide, coal, oil and all organic compounds)
carbon cycle(The cycle of carbon in the biosphere, in which plants convert carbon dioxide to organic compounds that are consumed by plants and animals, and the carbon is returned to the biosphere in inorganic form by processes of respiration and decay)
