nitrous oxide

American  

noun

Chemistry, Pharmacology.

nitrous oxides plural

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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Other Word Forms

Noun Inflected Forms

• nitrous oxides
  plural

Etymology

Origin of nitrous oxide

First recorded in 1790–1800

Example Sentences

See Examples For:

nitrous oxide

A 2024 report by the United Nations Environment Programme and the Food and Agriculture Organization warned that rising nitrous oxide emissions linked to fertiliser use are threatening climate goals.

From Barron's ● Jun. 16, 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

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

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