noun
: a colorless odorless very toxic gas CO that burns to carbon dioxide with a blue flame, that is formed as a product of the incomplete combustion of carbon (as in water gas and producer gas, in the exhaust gases from internal-combustion engines, and in the gases from the detonation of explosives), and that is used chiefly in the synthesis of carbonyls (as nickel carbonyl in the refining of nickel), phosgene, and many organic compounds (as hydrocarbons for fuels, methanol and higher alcohols, aldehydes, and formates) — see carbonylhemoglobin