hydrogen
noun
hy·dro·gen
ˈhī-drə-jən 
-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
Examples of hydrogen in a Sentence
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National Highways confirmed that the machine, operated by Skanska and supplied by Flannery Plant Hire, is powered by hydrogen from Ryze.
—
Sujita Sinha, Interesting Engineering, 3 Oct. 2025
Also losing out are companies that produce solar energy, electric vehicles and hydrogen power — among others.
—Rachel Frazin, The Hill, 3 Oct. 2025
One getting defunded is reportedly a huge hydrogen project in northwest that would also serve Montana.
—James Bickerton, MSNBC Newsweek, 3 Oct. 2025
Planet Earth, this early on, likely has a volatile early atmosphere, dominated by hydrogen, helium, water vapor, ammonia, and methane.
—Ethan Siegel, Big Think, 2 Oct. 2025
See All Example Sentences for hydrogen
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Sujita Sinha, Interesting Engineering, 3 Oct. 2025
Also losing out are companies that produce solar energy, electric vehicles and hydrogen power — among others.
—Rachel Frazin, The Hill, 3 Oct. 2025
One getting defunded is reportedly a huge hydrogen project in northwest that would also serve Montana.
—James Bickerton, MSNBC Newsweek, 3 Oct. 2025
Planet Earth, this early on, likely has a volatile early atmosphere, dominated by hydrogen, helium, water vapor, ammonia, and methane.
—Ethan Siegel, Big Think, 2 Oct. 2025
See All Example Sentences for hydrogen
Cite this Entry
“Hydrogen.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/hydrogen. Accessed 10 Oct. 2025.
Copy CitationKids Definition
hydrogen
noun
hy·dro·gen
ˈhī-drə-jən
: 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
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
: 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
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