Oxygen
noun ·Common ·High school level
Definitions
- 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. countable, uncountable
"Holonyms: dioxygen, O₂, oxygen (loose sense)"
- 2 a nonmetallic bivalent element that is normally a colorless odorless tasteless nonflammable diatomic gas; constitutes 21 percent of the atmosphere by volume; the most abundant element in the earth's crust wordnet
- 3 Molecular oxygen (O₂), a colorless, odorless gas at room temperature. countable, uncountable
"Meronym: oxygen (strict sense)"
- 4 A mixture of oxygen and other gases, administered to a patient to help them breathe. countable, uncountable
- 5 An atom of this element. countable
"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."
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- 6 A condition or environment in which something can thrive. countable, figuratively, uncountable
"Silence is the oxygen of shame."
Example
More examples"Oxygen from the air dissolves in water."
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.
Related phrases
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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.