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 compare deuterium, tritium
hydrogenous 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.
However, the nuclei of some atoms of hydrogen feature one proton and one neutron, too. Keith Cooper, Space.com, 17 Oct. 2025 The cells convert natural gas, hydrogen, or biogas into electricity through a clean electro-chemical process rather than dirty combustion. Jordan Blum, Fortune, 16 Oct. 2025 If water could be extracted, humans could use it for drinking, breathing and as a source of hydrogen and oxygen for rocket fuel. Eric Lagatta, USA Today, 16 Oct. 2025 Other technologies, notably hydrogen, are also competitors to heat batteries. Bloomberg, Mercury News, 16 Oct. 2025 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

Browse Nearby Words

Cite this Entry

“Hydrogen.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/hydrogen. Accessed 21 Oct. 2025.

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 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 adjective

More from Merriam-Webster on hydrogen

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