Definition of oxygen noun from the Oxford Advanced Learner's Dictionary

 

oxygen

 noun
noun
BrE BrE//ˈɒksɪdʒən//
 
; NAmE NAmE//ˈɑːksɪdʒən//
 
[uncountable](symbol O)
 
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a chemical element. Oxygen is a gas that is present in air and water and is necessary for people, animals and plants to live. Word Origin late 18th cent.: from French (principe) oxygène ‘acidifying constituent’ (because at first it was held to be the essential component in the formation of acids).Extra examples After dark the plants stop producing oxygen. The patient didn’t seem to be getting enough oxygen. There was a risk the brain might be starved of oxygen. the blood which carries oxygen to the brain