ox ‧ y ‧ gen /ˈɒksɪdʒ ə n $ ˈɑːk-/ BrE AmE noun [uncountable]
[ Date: 1700-1800 ; Language: French ; Origin: oxygène , from Greek oxys 'sharp, acid' + French -gène 'forming' ; because it was believed that oxygen forms part of all acids ]
a gas that has no colour or smell, is present in air, and is necessary for most animals and plants to live. It is a chemical ↑ element : symbol O