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oxygen

nouncommon in dialogue

  • United Kingdom//ˈɒksɪd͡ʒən//
  • United States//ˈɑksɪd͡ʒən//
  • United States//ˈɑksəd͡ʒən//
  • Australia//ˈɔksɪd͡ʒən//

The 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.

noun

  1. 1

    The 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)

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

  2. 2

    Molecular oxygen (O₂), a colorless, odorless gas at room temperature.

    Meronym: oxygen (strict sense)

    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.

  3. 3

    A mixture of oxygen and other gases, administered to a patient to help them breathe.

  4. 4

    An 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.

  5. 5

    figurativeA condition or environment in which something can thrive.

    Silence is the oxygen of shame.

    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.

Etymology

Etymology tree Proto-Indo-European *h₂eḱ-der.? Ancient Greek ὀξύς (oxús) Proto-Indo-European *ǵenh₁- Proto-Indo-European *-os Proto-Indo-European *ǵénh₁os Proto-Hellenic *génos Ancient Greek γένος (génos) French oxygènebor. English oxygen Borrowed from French oxygène (originally in the form principe oxygène, a variant of principe oxigine ‘acidifying principle’, suggested by Lavoisier), from Ancient Greek ὀξύς (oxús, “sharp”) + γένος (génos, “birth”), referring to oxygen's supposed role in the formation of acids. By surface analysis, oxy- + -gen.

Forms

plural
oxygens
The neighbouring pagesAlphabetical order follows the rules of the language, not byte values: an accent decides only between two otherwise identical words, and Spanish files Ñ as a letter of its own.

Lexical content from Wiktionary, under CC BY-SA 4.0 · Source entry · Data version 2026-08-23

Rank among the words of the OpenSubtitles 2018 corpus — film and television subtitles, so spoken rather than written usage (CC BY-SA 3.0).