noun
hydrogen
HYD-ruhjn
noun
1
The lightest chemical element, with the symbol H and atomic number 1.
"Hydrogen and oxygen combine to form water."
2
The colourless, odourless, highly flammable gas made of this element, found as a molecule of two hydrogen atoms.
"Some buses now run on hydrogen fuel cells instead of diesel."
How to Use Hydrogen
Learner’s notesIn plain EnglishThe simplest and lightest element there is, and the main ingredient (along with oxygen) of water.
Common pairings
hydrogen fuel
hydrogen atom
hydrogen peroxide
Word Forms
hydrogens plural
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_____ and oxygen combine to form water.
Etymology
Coined in French by chemists Guyton de Morveau and Lavoisier from Greek hydro- ("water") plus -gene ("producer of"), because burning hydrogen produces water.