carbon dioxidenoun [U]uk us (symbol CO2)
- Plants absorb carbon dioxide during photosynthesis.
- A molecule of carbon dioxide (CO2) has one carbon atom and two oxygen atoms.
- Microbes decompose organic waste into a mixture of methane and carbon dioxide.
- The increased use of natural gas will help reduce carbon dioxide emissions.
- There has been a sudden and worrying rise in the level of carbon dioxide in the atmosphere.