Longman Dictionary of Contemporary English homepage

Date: 1700-1800
Language: French
Origin: hydrogène, from hydro- ( HYDRO-) + -gène 'producing'; because it produces water when it is burned

hydrogen

 noun
     
NEW! See related topics: ELEMENTS
hy‧dro‧gen [uncountable]
HCE a colourless gas that is the lightest of all gases, forms water when it combines with oxygen, and is used to produce ammonia and other chemicals. It is a chemical element: symbol H
Definition from the Longman Dictionary of Contemporary English
Advanced Learner's Dictionary.
 
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