hydrogen

noun hy·dro·gen \ ˈhī-drə-jən , -dər- \

Updated on: 22 May 2018

Definition of hydrogen

: a nonmetallic element that is the simplest and lightest of the elements, is normally a colorless odorless highly flammable diatomic gas, and is used especially in synthesis — see Chemical Elements Table — compare deuterium, tritium

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hydrogenous

play \hī-ˈdrä-jə-nəs\ adjective

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See hydrogen defined for kids

Recent Examples of hydrogen from the Web

If a plume vented water vapor from the moon, some of the water’s constituent hydrogen and oxygen would become charged by being stripped of electrons by the radiation belts that surround Jupiter.

— ramin skibba, Scientific American, "Decades-Old Data Unveils Plumes Spewing from Europa," 14 May 2018
The sail will run into a variety of energetic particles in the interplanetary and interstellar medium, but most of these will be hydrogen and helium.

— john timmer, Ars Technica, "The material science of building a light sail to take us to Alpha Centauri," 7 May 2018
Then ultraviolet radiation dissociated the water vapor in the upper Venusian atmosphere, turning it into molecular oxygen and hydrogen.

— scott denning, Washington Post, "May the 4th be with Earth, a perfect planet that’s not too Hoth or Tatooine," 4 May 2018
In 2005, President George W. Bush signed a law that created a 30 percent credit for investing in fuel cells, which combine hydrogen and oxygen to create an electric current.

— jim tankersley, New York Times, "The Trump Tax Cuts Hurt This Manufacturer. It Kept On Lobbying.," 9 Feb. 2018
The start-up is aiming to deliver a long-haul hydrogen-electric truck to customers as early as 2020.

— nathan bomey, USA TODAY, "Tesla accused of violating Nikola Motor patents with electric semi truck, sues for $2B," 2 May 2018
Nikola Motor is designing and building its own driverless, hydrogen fuel cell–powered Class 8 truck.

— kirsten korosec, Fortune, "Tesla Hit With a $2 Billion Lawsuit for Allegedly Stealing Nikola's Hydrogen Truck Design," 2 May 2018
The lack of ozone means that ultraviolet energy can penetrate the atmosphere and bust up water molecules into hydrogen and oxygen.

— jeffrey kluger, Time, "Why Earthlings Are So Obsessed With Mars," 1 May 2018
The diagram has already helped researchers learn to distinguish white dwarfs dominated by hydrogen and white dwarfs dominated by helium.

— jason daley, Smithsonian, "New Star Map Could Change Everything We Know About the Milky Way," 25 Apr. 2018

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.

Origin and Etymology of hydrogen

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

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First Known Use: 1788

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HYDROGEN Defined for English Language Learners

hydrogen

noun

Definition of hydrogen for English Language Learners

: a chemical element that has no color or smell and that is the simplest, lightest, and most common element

HYDROGEN Defined for Kids

hydrogen

noun hy·dro·gen \ ˈhī-drə-jən \

Definition of hydrogen for Students

: a colorless, odorless, and tasteless flammable gas that is the lightest of the chemical elements

History for hydrogen

When hydrogen is burned it combines with oxygen to make water. That fact accounts for the name of this gas. The word hydrogen was formed from two Greek roots. The first, hydro-, means “water,” and the second, -gen, means “giving rise to, producing.”

Medical Dictionary

hydrogen

noun hy·dro·gen \ ˈhī-drə-jən \

medical Definition of hydrogen

: 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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