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

Compare meaning

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

• carbon monoxide vs. carbon dioxide

Example Sentences

See Examples For:

carbon monoxide

EPA officials said on a call Monday that the change will not include pollutants that directly harm health such as carbon monoxide and nitrogen dioxide, which are regulated separately.

From Los Angeles Times ● Sep. 14, 2026

But modern gas generators produce upward of 90% less fine particulate matter, sulfur dioxide and carbon monoxide than a steel mill.

From The Wall Street Journal ● Aug. 31, 2026

The first flames would have reacted with the flammable materials to produce carbon monoxide and hydrogen cyanide, often known as the "toxic twins" of fire smoke, he explains.

From BBC ● Jul. 14, 2026

State media initially reported four deaths and dozens trapped after levels of carbon monoxide -- a highly toxic, odourless gas -- in the mine were found to have "exceeded limits".

From Barron's ● May 23, 2026

With the apartment windows open, you can taste the carbon monoxide rising from the street below.

From "The Girl on the Train" by Paula Hawkins