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

But excessive tonnages of carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride are changing Earth’s climate.

From The Wall Street Journal • Feb. 24, 2026

Automated chambers tracked CO2, methane, and nitrous oxide emissions multiple times per day throughout the growing season.

From Science Daily • Feb. 22, 2026

Meanwhile, fertiliser use emits nitrous oxide -- the third-most-potent greenhouse gas after methane and carbon dioxide.

From Barron's • Nov. 11, 2025

Ye has since sued his dentist for "recklessly" supplying Ye with "dangerous amounts of nitrous oxide".

From BBC • May 27, 2025

Chlorine is green and is deadly; nitrous oxide is colorless and makes people giggle.

From "Zero: The Biography of a Dangerous Idea" by Charles Seife