nitrous oxide

noun

: a colorless gas N2O that when inhaled produces loss of sensibility to pain preceded by exhilaration and sometimes laughter, that is used especially as an anesthetic in dentistry and as a fuel, and that is an atmospheric pollutant and greenhouse gas produced by combustion

called also laughing gas

compare nitric oxide

Examples of nitrous oxide in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Advertisement Concentrations of greenhouse gases—including carbon dioxide, methane, and nitrous oxide—all reached record levels in 2026, the researchers say. — Simmone Shah, Time, 14 Oct. 2026 Carbon dioxide in the atmosphere, a by-product of burning fossil fuels, has reached record-high levels (428 parts per million), as have other greenhouse gases such as methane (1,940 parts per billion) and nitrous oxide (340 parts per billion). — Jackie Flynn Mogensen, Scientific American, 14 Oct. 2026 The City Council’s ban on nitrous oxide sales by cannabis and tobacco retailers goes beyond state law by making violations a misdemeanor. — Melissa Gomez, Los Angeles Times, 13 Oct. 2026 Los Angeles County deputies arrested 10 people for illegally selling and possessing nitrous oxide at a Bellflower gas station. — Matthew Rodriguez, CBS News, 12 Oct. 2026 See All Example Sentences for nitrous oxide

Word History

First Known Use

1798, in the meaning defined above

Time Traveler
The first known use of nitrous oxide was in 1798

Rhymes for nitrous oxide

See All Rhymes for nitrous oxide

Browse Nearby Words

nitrous ether
nitrous oxide
nitrous vitriol
See all Nearby Words

Cite this Entry

“Nitrous oxide.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/nitrous%20oxide. Accessed 19 Oct. 2026.

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Kids Definition

nitrous oxide

noun
: a colorless gas that when inhaled causes loss of the ability to feel pain and sometimes produces laughter and is used especially in dentistry

called also laughing gas

Medical Definition

nitrous oxide

noun
: a colorless gas N2O that when inhaled produces loss of sensibility to pain preceded by exhilaration and sometimes laughter and is used especially as an anesthetic in dentistry

called also laughing gas

More from Merriam-Webster on nitrous oxide

Britannica.com: Encyclopedia article about nitrous oxide

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