hydrogen

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noun hy·dro·gen \ˈhī-drə-jən, -dər-\

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 element table — compare deuterium, tritium

hydrogenous

play \hī-ˈdrä-jə-nəs\ adjective

See hydrogen defined for English-language learners

See hydrogen defined for kids

Recent Examples of hydrogen from the Web

The largest hydrogen bomb ever exploded, the Tsar Bomb in 1961 by the old Soviet Union, yielded 57 megatons.

— tom skilling, chicagotribune.com, "Ask Tom: Is collision with asteroid Apophis likely?", 5 July 2017
So the algae uses the photosynthetic energy to make lipids, which are made up of hydrogen and carbon.

— bradley j. fikes, sandiegouniontribune.com, "Synthetic Genomics and ExxonMobil double biofuel yield from algae", 19 June 2017
This is because of the inflammable hydrogen used in the Zeppelin.

— kurt chandler, chicagotribune.com, "Son traces his father's steps through Europe, shares his impressions with the world", 16 June 2017
Paris also examined several other similar comets and found the same type of hydrogen cloud and the same type of signal, which means that even if comet 266P wasn't the specific source of the Wow! signal, another comet is most likely the culprit.

— avery thompson, Popular Mechanics, "The Mystery Behind a 40-Year-Old Signal From Outer Space May Finally Be Solved", 5 June 2017
In China, Brown will spread the gospel of California’s auto policies, including a state rule requiring an increase in annual sales of zero-emission vehicles powered by batteries or hydrogen.

— john lippert, Bloomberg.com, "Trump's Toughest Climate Foe Taking Clean-Air Crusade to China", 1 June 2017
The atmosphere is toxic with high concentrations of carbon dioxide, hydrogen sulfide and other gases.

— marjie lambert, miamiherald, "World of ‘Avatar’ comes to life at Disney World and it doesn’t look like any garden you’ve seen", 30 May 2017
Farady, named for the English scientist Michael Faraday, who invented the rubber balloon in 1824 for use in his research with hydrogen.

— sacbee, "Today in Sacramento: Here’s what you need to know for Tuesday", 30 May 2017
Scientists worried at one point that a hydrogen bubble forming inside the reactor would explode with catastrophic consequences.

— marc levy, The Christian Science Monitor, "Owner threatens to close Three Mile Island nuclear plant as natural gas boom cuts profits", 30 May 2017

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

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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

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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

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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; element table