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

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

The centers are also adding nitrous oxide, or laughing gas, for intrauterine device insertions.

From The Wall Street Journal • Mar. 1, 2026

When soil is damp but not completely waterlogged, nitrogen breakdown may stop midway, producing nitrous oxide instead of harmless nitrogen gas.

From Science Daily • Feb. 22, 2026

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

From BBC • May 27, 2025

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