hy·​dro·​gen ˈhī-drə-jən How to pronounce hydrogen (audio)
: 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 see Chemical Elements Table compare deuterium, tritium
hydrogenous adjective

Example Sentences

Recent Examples on the Web The team also plans to build a yacht with a hydrogen fuel cell. Rachel Cormack, Robb Report, 1 Mar. 2023 In May 1937, the golden age of transcontinental passenger airships came to a catastrophic end in roughly 30 seconds after a spark set the hydrogen fuel on the Hindenburg ablaze, killing 36. Richard Galant, CNN, 5 Feb. 2023 The best PECs can convert nearly one-quarter of sunlight’s energy into hydrogen fuel. Byrobert F. Service, science.org, 4 Jan. 2023 The team could use the converted light to drive a chemical reaction that produces hydrogen fuel from methanol. IEEE Spectrum, 30 Dec. 2022 The Toyota space includes its hydrogen fuel cell vehicle, the Mirai. San Diego Union-Tribune, 29 Dec. 2022 At the same time, Volkswagen has struggled to get its EV strategy on track, while Toyota is still hedging its bets, betting on hybrids and hydrogen fuel cells, as well as EVs. Emily Yamamoto, Bloomberg.com, 20 Dec. 2022 Europe’s activity appears to be accelerating a global transition toward cleaner technologies, the agency added, as countries respond to Russia’s invasion of Ukraine by embracing hydrogen fuels, electric vehicles, heat pumps and other green energies. Patricia Cohen, New York Times, 1 Nov. 2022 Nikola slid about 5% after the maker of electric and hydrogen fuel-cell heavy trucks reported softer-than-expected results and 20 customer deliveries in the fourth quarter. Amrith Ramkumar, WSJ, 23 Feb. 2023 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'hydrogen.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History


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

Dictionary Entries Near hydrogen

Cite this Entry

“Hydrogen.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/hydrogen. Accessed 22 Mar. 2023.

Kids Definition


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

Medical Definition


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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