carbon dioxide

noun

: a heavy colorless gas CO₂ that does not support combustion, dissolves in water to form carbonic acid, is formed especially in animal respiration and in the decay or combustion of animal and vegetable matter, is absorbed from the air by plants in photosynthesis, and is used in the carbonation of beverages

Examples of carbon dioxide in a Sentence

Recent Examples on the Web

The suits all carry a supply of emergency oxygen and can scrub carbon dioxide from the environment, providing breathable air to the astronauts for up to six days, if needed. —Tom Costello, NBC news, 10 Apr. 2026

Nuclear reactors do not produce carbon dioxide while operating. —Los Angeles Times, 8 Apr. 2026

These function as powerful natural sinks to absorb carbon dioxide and help regulate the climate. —ABC News, 8 Apr. 2026

The crew tested the spacecraft's life support systems, like the carbon dioxide scrubbers, and donned their spacesuits midflight — which future astronauts might have to do in an emergency. —Brendan Byrne, NPR, 6 Apr. 2026

Word History

First Known Use

1867, in the meaning defined above

Rhymes for carbon dioxide

• acetamide
• acetonide
• acidified
• antimonide
• beatified
• benzaldehyde
• borohydride
• chalcogenide
• commodified
• decalcified
• declassified
• disaccharide

Kids Definition

carbon dioxide

noun

: a heavy colorless gas CO₂ that is formed especially by the burning and breaking down of organic substances (as in animal respiration), is absorbed from the air by plants in photosynthesis, and has many industrial uses

Medical Definition

carbon dioxide

noun

: a heavy colorless gas CO₂ that does not support combustion, dissolves in water to form carbonic acid, is formed especially in animal respiration and in the decay or combustion of animal and vegetable matter, is absorbed from the air by plants in photosynthesis, and is used in the carbonation of beverages