Added 9 October 2026

hydrogen

/ˈhaɪdɹəd͡ʒ(ə)n/ noun

In Latin: hydrogenium Coined: 1737, by Louis-Bernard Guyton Wiktionary

noun Definition from Wiktionary (CC BY-SA). Pronunciation from Wiktionary, via Kaikki.org. More about hydrogen at Wordnik → Where our words come from →

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.
An atom of this element.
Each carbon of the ring has one hydrogen attached except for the fourth one, which is bonded to a substituent.
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.

Borrowed from French hydrogène (“hydrogen”), coined by the French chemists Louis-Bernard Guyton de Morveau (1737–1816) and Antoine Lavoisier (1743–1794) from hydro- (prefix meaning ‘water’) + -gène (suffix denoting a producer of something), from the fact that water is produced as a compound when hydrogen is oxidized. * The prefix hydro- is borrowed from Ancient Greek ῠ̔δρο- (hŭdro-), from ῡ̆̔́δωρ (hū̆́dōr, “water”), ultimately from Proto-Indo-European *wed- (“water”).