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

The levels of carbon dioxide, methane and nitrous oxide in the atmosphere all increased in 2025. —Michael Wysession, Fortune, 6 Mar. 2026

The levels of carbon dioxide, methane and nitrous oxide in the atmosphere all increased in 2025. —Michael Wysession, The Conversation, 5 Mar. 2026

The landmark environmental regulation officially determined that greenhouse gases — carbon dioxide, methane, nitrous oxide, hydrofluorocarbons —threaten public health and welfare. —Stephen Underwood, Hartford Courant, 2 Mar. 2026

The Senate Appropriations Committee also removed provisions related to stricter regulation of the supplements kratom and 7-Hydroxymitragynine, otherwise known as 7-OH, from a bill cracking down on the sale of nitrous oxide. —Kate Wolffe, Sacbee.com, 23 Jan. 2026

Word History

First Known Use

1798, in the meaning defined above

Rhymes for nitrous oxide

• acetamide
• acetonide
• acidified
• antimonide
• beatified
• benzaldehyde
• borohydride
• chalcogenide
• commodified
• decalcified
• declassified
• disaccharide

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