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 levels of carbon dioxide, methane and nitrous oxide in the atmosphere all increased in 2025. —Michael Wysession, Fortune, 6 Mar. 2026

The water is equivalent to carbon dioxide in the atmosphere, and humans have essentially stuck a hose into the pool and every year been turning up the faucet — so the water is rising faster and faster. —Laura Paddison, CNN Money, 6 Mar. 2026

Living Carbon Capture Dye Systems has created a dyeing process that uses cyanobacteria to capture atmospheric carbon dioxide and convert it into textile dyes. —Alexandra Harrell, Sourcing Journal, 5 Mar. 2026

The levels of carbon dioxide, methane and nitrous oxide in the atmosphere all increased in 2025. —Michael Wysession, The Conversation, 5 Mar. 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