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.
This star has lost most — or all — of its outer layers of hydrogen, leaving behind a core made up mostly of helium. Charles Q. Choi, Space.com, 22 May 2025 The hydrogen gas has been building within the Earth's crust for the past billion years, the researchers said. Julia Jacobo, ABC News, 16 May 2025 This frequently involves the extraction of coal's hydrogen for use in other chemicals, leaving the carbon to be emitted as carbon dioxide. John Timmer, ArsTechnica, 15 May 2025 That is, a fusion reaction that fuses a hydrogen nucleus and a boron-11 atom instead of two atoms of the hydrogen isotopes deuterium and tritium. David Szondy may 10, New Atlas, 10 May 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 28 May. 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

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