hydrogen

Meanings

1. 1
   noun

   a nonmetallic univalent element that is normally a colorless, odorless, and highly flammable diatomic gas

   The warning label on the hydrogen balloon said not to bring the balloon near open flames.

2. 2
   noun

   The lightest chemical element (symbol H), with an atomic number of 1 and atomic weight of 1.008.

   Our professor then reminded us that a hydrogen ion is merely a proton, and thus we should think about acid-base theory as we consider this problem further.

3. 3
   noun

   Molecular hydrogen (sense 1; symbol H₂), a colourless, odourless and flammable gas at room temperature.

   A large tank of hydrogen constituted most of the bulk of that rocket.

4. 4
   noun

   Synonym of protium (“the lightest and most common isotope of hydrogen (sense 1; symbol H, ¹H, or 11H), as contrasted with deuterium and tritium”).

   Both hydrogen and deuterium are present in every glass of water that you drink, but the amount of deuterium is rather small.

Etymology

Etymology tree Proto-Indo-European *wed- Proto-Indo-European *-r̥ Proto-Indo-European *wódr̥ Proto-Hellenic *údōr Ancient Greek ῡ̆̔́δωρ (hū̆́dōr) Ancient Greek ὑδρο- (hudro-)lbor. French hydro- Proto-Indo-European *ǵenh₁- Proto-Indo-European *-os Proto-Indo-European *ǵénh₁os Proto-Hellenic *génos Ancient Greek γένος (génos) Proto-Indo-European *-os Proto-Indo-European *-ēs Ancient Greek -ης (-ēs) Ancient Greek -γενής (-genḗs)lbor. French -gène French hydrogènebor. English hydrogen Borrowed from French hydrogène (“hydrogen”), coined by the French chemists Louis-Bernard Guyton de Morveau (1737–1…