- any of several gaseous mixtures consisting essentially of carbon monoxide and hydrogen, used in the synthesis of chemical compounds, as ammonia and alcohols.
- a mixture of carbon dioxide, carbon monoxide, and hydrogen formerly made by using water gas and reacting it with steam to enrich the proportion of hydrogen for use in the synthesis of ammonia
- a similar mixture of gases made by steam reforming natural gas, used for synthesizing organic chemicals and as a fuel
