atomic number 6, carbon, C - an abundant nonmetallic tetravalent element occurring in three allotropic forms: amorphous carbon and graphite and diamond; occurs in all organic compounds

fossil fuel - fuel consisting of the remains of organisms preserved in rocks in the earth's crust with high carbon and hydrogen content

oil - a slippery or viscous liquid or liquefiable substance not miscible with water

resid, residual oil - oil products that remain after petroleum has been distilled