oxygen

plural oxygens

1. countableuncountablechemistryThe chemical element (symbol O) with an atomic number of 8 and relative atomic mass of 15.9994. It is a colorless and odorless gas. Sometimes called elemental oxygen to distinguish it from molecular oxygen.

   Holonyms: dioxygen, O₂, oxygen (loose sense)

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   By molar fraction, calcium oxide contains equal parts calcium and oxygen.

   Synonyms: sourstuff, E948[packaging gas]]>

2. countableuncountableloose but very common; even in formal use; loose but very common; even in formal useMolecular oxygen (O₂), a colorless, odorless gas at room temperature.

   Meronym: oxygen (strict sense)

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   About 21% of the air you breathe is oxygen.

   Oxygen levels on Earth skyrocketed 2.4 billion years ago, when cyanobacteria evolved photosynthesis: the ability to convert water and carbon dioxide into carbohydrates and waste oxygen using solar energy. The evolutionary precursor of photosynthesis is still under debate, and a new study sheds light.

   2013 September-October, Katie L. Burke, “In the News”, in American Scientist, archived from the original on 03 Sep 2013

   Just like eating halal is not a choice for our Muslim brothers and sisters, for us, eating kosher is not voluntary; it’s who we are and as necessary as the oxygen we need for sustenance.

   2020 August 20, Eliezer Brand, “ICE is forcing Muslims to eat pork. My fellow Orthodox Jews: This is our fight!”, in The Forward, archived from the original on 24 Oct 2020

   Synonyms: dioxygen, mul:O₂

3. countableuncountablemedicineA mixture of oxygen and other gases, administered to a patient to help them breathe.
4. countableAn atom of this element.

   Look first at any structure to see if there is a carbon with two oxygens attached. Hemiacetals, hemiketals, acetals, and ketals are all alike in that regard.

   2013, Spencer L. Seager, Michael R. Slabaugh, Chemistry for Today: General, Organic, and Biochemistry, page 479

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   Dodecylbenzenesulfonic acid is a long name for a long molecule. The ring on the left contributes the “benzene” part of the name, and the sulfur atom with three oxygens bonded to it contributes the “sulfonic acid” part.

   2014, Theodore Gray, photography by Nick Mann, Molecules: The Elements and the Architecture of Everything, 2018 Paperback Edition, page 65

5. countablefigurativelyuncountableA condition or environment in which something can thrive.

   Silence is the oxygen of shame.

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   They hoped to starve the terrorists of the oxygen of publicity.

   I found myself longing for more than two minutes with the girlfriend, the ex-wife, the assistant, the board member, let alone one of the many staff at the house – anyone to de-center a perspective that has already claimed far too much oxygen in the public sphere.

   2025 June 2, Adrian Horton, “Tech-bro satire Mountainhead is an insufferable disappointment”, in The Guardian, →ISSN, archived from the original on 23 Jul 2025

   “Attention is Trump’s oxygen,” said Mark McKinnon, who was a media consultant for President George W. Bush and Senator John McCain, Republican of Arizona.

   2026 September 21, Peter Baker, quoting Mark McKinnon, “Trump Faces the Sting of a Media Boycott After Press Pool Withdrawal”, in The New York Times, →ISSN