English Reference
noun

hydrogen

n.
US /ˈhaɪdɹədʒən/ UK /hˈaɪdɹədʒən/ hy·dro·gen UK spelling hydrogen's, hydrogen's

  1. 01 B1 Intermediate Technical Science

    the simplest and lightest chemical element, found in water and all living things.

    the chemical element with atomic number 1 and symbol H. Uncountable when referring to the element in a general or chemical sense.

    Simple

    Hydrogen is the most common element in the entire universe.

    In context

    Hydrogen atoms consist of a single proton and a single electron, making it the simplest and most abundant element in the cosmos.

    Usage

    Often used as a modifier in compound nouns like 'hydrogen atom' or 'hydrogen bond'.

  2. 02 B2 Upper Intermediate Technical Science

    a gas with no colour or smell that burns very easily and can be used as fuel.

    molecular hydrogen (H₂) existing as a colourless, odourless, and highly flammable gas at standard temperature and pressure.

    Simple

    The car runs on hydrogen instead of petrol to help the environment.

    In context

    The experimental aircraft was powered by liquid hydrogen, which requires specialised storage tanks to maintain extremely low temperatures.

    Usage

    Commonly used with verbs like 'burn', 'store', or 'produce'.

Usage hydrogen atoms · hydrogen gas

Scientists have created an unusually corrosion-resistant stainless steel that could replace costly titanium components used to produce green hydrogen.

ScienceDaily· 11 Aug 2026

Because hydrogen is so abundant in the universe, the line is easy for radio telescopes to detect.

The Guardian· 11 Aug 2026

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”). The suffix -gène is borrowed from Ancient Greek -γενής (-genḗs, suffix meaning ‘born in a certain condition or place’), from γένος (génos, “descendant, offspring; race; etc.”) (ultimately from Proto-Indo-European ǵenh₁- (“to beget, produce; to give birth”)) + -ης (-ēs, suffix forming some third-declension adjectives). By surface analysis, hydro- (prefix meaning ‘water’) + -gen (suffix denoting a producer of something).

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin ine-pro *ǵenh₁-
Level C1 · Advanced
Frequency Frequent
Updated