Nitrous Oxide. Laughing Gas . Nitrogen Protoxide . Gas, Laughing . Oxide, Nitrous . Nitrogen oxide (N2O). A colorless, odorless gas that is used as an anesthetic and analgesic. High concentrations cause a narcotic effect and may replace oxygen, causing death by asphyxia. It is also used as a food aerosol in the preparation of whipping cream. . 0.64