carbon monoxide

American  

noun

1. a colorless, odorless, poisonous gas, CO, that burns with a pale-blue flame, produced when carbon burns with insufficient air: used chiefly in organic synthesis, metallurgy, and in the preparation of metal carbonyls, as nickel carbonyl.

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carbon monoxide British  

noun

1. a colourless odourless poisonous flammable gas formed when carbon compounds burn in insufficient air and produced by the action of steam on hot carbon: used as a reducing agent in metallurgy and as a fuel. Formula: CO

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Etymology

Origin of carbon monoxide

First recorded in 1870–75

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Compare meaning

How does carbon-monoxide compare to similar and commonly confused words? Explore the most common comparisons:

• carbon monoxide vs. carbon dioxide

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Example Sentences

See Examples For:

carbon monoxide

The expanded model also correctly identified methanol and carbon monoxide as major products, bringing its predictions into agreement with experimental findings.

From Science Daily ● Oct. 14, 2026

When thermal runaway starts, the process can continue for days, with the potential for batteries to release toxic gases such as hydrogen fluoride, hydrogen chloride and carbon monoxide.

From Los Angeles Times ● Sep. 25, 2026

Smoke resulting from incomplete burning contains dense, lethal concentrations of carbon monoxide.

From BBC ● Sep. 11, 2026

Emissions of carbon monoxide, nitrous oxide and dangerous particulate matter increased by 196%, 111%, and 139% respectively.

From The Wall Street Journal ● Sep. 7, 2026

There are small traces of nitrogen, water vapor, argon, carbon monoxide and other gases, but the only hydrocarbons or carbohydrates present are there in less than 0.1 parts per million.

From "Cosmos" by Carl Sagan

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