nitrous oxide

American  

noun

Chemistry, Pharmacology.

1. a colorless, sweet-smelling, sweet-tasting, nonflammable, slightly water-soluble gas, N 2 O, that sometimes produces a feeling of exhilaration when inhaled: used chiefly as an anesthetic in dentistry and surgery, in the manufacture of chemicals, and as an aerosol.

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nitrous oxide British  

noun

1. Systematic name: dinitrogen oxide.  Also called: laughing gas.  a colourless nonflammable slightly soluble gas with a sweet smell: used as an anaesthetic in dentistry and surgery. Formula: N 2 O

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nitrous oxide Scientific  

1. A colorless, sweet-smelling gas. It is used as a mild anesthetic, often called laughing gas. Nitrous oxide occurs naturally in the atmosphere and is a greenhouse gas. Chemical formula: N ₂ O.

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Etymology

Origin of nitrous oxide

First recorded in 1790–1800

Example Sentences

Banned items include weapons, fireworks, flares, gas canisters, laser pens, camping chairs, umbrellas, flagpoles, air horns, megaphones, nitrous oxide, and excessive food and cigarettes security would think was more than "personal use".

From BBC • Jun. 10, 2026

Entonox is a mixture of nitrous oxide and oxygen that is used as pain relief for women giving birth.

From BBC • May 18, 2026

However the increase in concentrations of heat-trapping greenhouse gases -- carbon dioxide, methane and nitrous oxide -- "to their highest level in at least 800,000 years" has "upset this equilibrium", the WMO said.

From Barron's • Mar. 23, 2026

“I think it makes a difference whether somebody would get a very effective and safe method of birth control,” Adamson said of the nitrous oxide.

From The Wall Street Journal • Mar. 1, 2026

It wasn’t until 1846 that anyone got around to finding a practical use for nitrous oxide, as an anesthetic.

From "A Short History of Nearly Everything" by Bill Bryson