hydrogen

noun

hy·​dro·​gen ˈhī-drə-jən How to pronounce hydrogen (audio)
-dər-
: a nonmetallic gaseous chemical element with atomic number 1 that is the simplest and lightest of the elements and that is used especially in the processing of fossil fuels and the synthesis of ammonia
—often used before another noun
hydrogen gas
hydrogen atoms
a hydrogen vehicle
the hydrogen industry
 see Chemical Elements Table see also green hydrogen compare deuterium, tritium
hydrogenous
hī-ˈdrä-jə-nəs How to pronounce hydrogen (audio)
adjective

Examples of hydrogen in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
This revealed that the globular clusters at the heart of our galaxy can be categorized in three distinct ways based upon their age and their metallicity, a measure of elements heavier than hydrogen and helium, which astronomers refer to as metals. — Robert Lea, Space.com, 24 Aug. 2026 Those photons then slammed into protons inside a liquid hydrogen target, producing showers of secondary particles. — Rupendra Brahambhatt, Interesting Engineering, 23 Aug. 2026 At the time, molecular structure wasn’t understood, but elements were, and both quinine and aniline contained carbon, hydrogen, and nitrogen. — Encyclopedia Britannica, 21 Aug. 2026 Symbiotica’s high-dose liposomal supplements — vitamin C, magnesium and Irish moss sachets — sit alongside Neuromints adaptogen mints and H2 hydrogen tablets. — Ritu Upadhyay, Footwear News, 21 Aug. 2026 See All Example Sentences for hydrogen

Word History

Etymology

French hydrogène, from hydr- + -gène -gen; from the fact that water is generated by its combustion

First Known Use

1788, in the meaning defined above

Time Traveler
The first known use of hydrogen was in 1788

Phrases Containing hydrogen

Rhymes for hydrogen

See All Rhymes for hydrogen

Browse Nearby Words

hydrogel
hydrogen
hydrogenase
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Cite this Entry

“Hydrogen.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/hydrogen. Accessed 28 Aug. 2026.

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Kids Definition

hydrogen

noun
hy·​dro·​gen ˈhī-drə-jən How to pronounce hydrogen (audio)
: a chemical element that is the simplest and lightest of all chemical elements and is normally found alone as a colorless odorless highly flammable gas having two atoms per molecule see element
hydrogenous
hī-ˈdräj-ə-nəs How to pronounce hydrogen (audio)
adjective
Etymology

from French hydrogène "hydrogen," from hydr- "water" and -gène "producer"; so called because when hydrogen gas burns, it combines with oxygen to produce water

Medical Definition

hydrogen

noun
hy·​dro·​gen ˈhī-drə-jən How to pronounce hydrogen (audio)
: a nonmetallic element that is the simplest and lightest of the elements and that is normally a colorless odorless highly flammable diatomic gas
—symbol H see deuterium, tritium Chemical Elements Table
hydrogenous
hī-ˈdräj-ə-nəs How to pronounce hydrogen (audio)
adjective

More from Merriam-Webster on hydrogen

Britannica.com: Encyclopedia article about hydrogen

Last Updated: - Updated example sentences
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