underground

adverb
un·​der·​ground | \ ˌən-dər-ˈgrau̇nd \

Definition of underground

 (Entry 1 of 3)

1 : beneath the surface of the earth
2 : in or into hiding or secret operation

underground

noun
\ ˈən-dər-ˌgrau̇nd \

Definition of underground (Entry 2 of 3)

1 : a subterranean space or channel
2 : an underground city railway system
3a : a movement or group organized in strict secrecy among citizens especially in an occupied country for maintaining communications, popular solidarity, and concerted resistive action pending liberation
b : a clandestine conspiratorial organization set up for revolutionary or other disruptive purposes especially against a civil order
c : an unofficial, unsanctioned, or illegal but informal movement or group especially : a usually avant-garde group or movement that functions outside the establishment

underground

adjective
un·​der·​ground | \ ˈən-dər-ˌgrau̇nd \

Definition of underground (Entry 3 of 3)

1 : being, growing, operating, or situated below the surface of the ground
2 : conducted by secret means
3a : existing outside the establishment an underground literary reputation
b : existing outside the purview of tax collectors or statisticians the underground economy
4a : produced or published outside the establishment especially by the avant-garde underground movies underground newspapers
b : of or relating to the avant-garde underground an underground moviemaker an underground theater

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Examples of underground in a Sentence

Adverb

They had been living underground as fugitives.

Noun

I've ridden on the New York subway, the Paris Metro, and the London Underground. joined the underground while still a teenager

Adjective

The drugs are supplied through an underground network. She loves the city's underground music scene.
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Recent Examples on the Web: Adverb

In early December, Chesapeake was threading a drill bit through sandstone more than 2 miles underground. Rebecca Elliott, WSJ, "Chesapeake Energy, Fracking Pioneer, Bet on Oil. Then Prices Plunged," 1 Jan. 2019 Massive Ordnance Penetrator, or GBU-57, was developed to attack hard targets buried deeply underground. Kyle Mizokami, Popular Mechanics, "Watch a Stealth Bomber Drop Two of World’s Largest Conventional Bombs," 27 Dec. 2018 The rail link would include either two or four tracks underground through the city’s downtown, connecting the city’s two major transportation hubs. Adam Vaccaro, BostonGlobe.com, "North-South Rail Link would cost $12 billion, maybe much, much more," 18 June 2018 Visitors enter through a separate building before descending underground and re-emerging to reach the gallery space. Alexandra Wolfe, WSJ, "Daniel Libeskind Thinks Buildings Should Tell Stories," 30 Nov. 2018 The missiles are stored underground to protect them from air and artillery attack. Kyle Mizokami, Popular Mechanics, "North Korea Appears to Be Expanding Nuclear Missile Program," 12 Nov. 2018 Located behind the existing structure, the Wall House is one-story above ground, with tons of space underground, bringing the total square footage of the property to 11,000. Jenny Xie, Curbed, "‘Livable version’ of Philip Johnson’s Glass House hits the market," 13 Sep. 2018 But those who respond in a controlling, authoritarian way risk driving teens underground, research shows. Sue Shellenbarger, WSJ, "The Minefield of Talking With Your Children About Sexting," 20 Oct. 2018 Ground unmanned vehicle operation is tough enough, with vertical challenges and broken terrain, but the subterranean realm adds an entirely new layer--particularly the difficulty in transmitting data underground. Kyle Mizokami, Popular Mechanics, "The U.S. Military Wants Drones To Fly Through Enemy Caves and Map Them," 4 Oct. 2018

Recent Examples on the Web: Noun

Like the kilogram standards, the Kibble balance is housed deep underground at NIST. Brian Resnick, Vox, "The world is about to redefine the kilogram," 15 Nov. 2018 The single-line, 15.5-mile heavy rail system runs above ground from Owings Mills to Mondawmin and underground between Mondawmin and Johns Hopkins Hospital. Colin Campbell, baltimoresun.com, "Transit union warned of unsafe Baltimore Metro tracks for several years," 22 June 2018 The pipeline from China to the U.S. is connected by an online marketplace that is moving commerce deeper underground on the dark web, where drug purchases can be made with anonymity. Kristina Davis, sandiegouniontribune.com, "Fentanyl has taken over America's drug market. Where is it coming from?," 17 June 2018 But even before the eruption, magma shifting around underground was already causing quakes, CNN meteorologist Judson Jones said. Holly Yan, CNN, "Here's what Hawaii's volcano eruption looks like -- by the numbers," 7 May 2018 The main house has an elevator, multiple patios, a 3-story rock waterfall and a swimming pool with a 40-foot-long underground waterslide that was inspired by the family’s many trips to Disneyland, Mr. Lynch said. Katherine Clarke, WSJ, "Investor Peter Lynch Auctions Arizona Golf Home After Listing Struggles," 31 Oct. 2018 The other projects that received funding include ones to store more water underground, including in parched Southern California, as well as ones to raise the heights of existing dams. Jim Carlton, WSJ, "California Awards $3 Billion in Water-Storage Projects," 24 July 2018 Scientists say the older lava is likely from magma that Kilauea has been storing underground since the volcano last erupted in 1955. Washington Post, "Faster-moving Hawaii lava gushes into sea, spews new danger," 20 May 2018 The most common location for those killed at home was in the bathroom (7.3 percent), basement or underground shelter (4 percent), a bedroom (4 percent) and hallway (4 percent). Leigh Morgan, AL.com, "April 27, 2011: Why did so many die that day?," 27 Apr. 2011

Recent Examples on the Web: Adjective

The need for such weapons first arose during the 1991 Gulf War, when U.S. and Coalition forces realized Saddam Hussein had buried much of Iraq’s command, control, and communications infrastructure in underground bunkers. Kyle Mizokami, Popular Mechanics, "Watch a Stealth Bomber Drop Two of World’s Largest Conventional Bombs," 27 Dec. 2018 Unlike Midge, however, May was a creature of the underground, rather than a visitor to it. Chloe Foussianes, Town & Country, "The Marvelous Mrs. Maisel," 16 Dec. 2018 Essentially, the system is made up of two parts—a geothermal heat pump and underground pipes—that use the steady ground temperature of 50 degrees Fahrenheit to heat and cool your home by moving heat from the earth to your home. Taylor Mead, House Beautiful, "You Can Save Serious Money By Powering Your Home Via Your Backyard," 5 Dec. 2018 In early 1945, he was shuffled to a camp near Dachau and put to work building underground bunkers. James R. Hagerty, WSJ, "Holocaust Survivor Rushed to Make Up for Lost Time and Lives," 2 Nov. 2018 A year ago, a deadly fire exposed Daniel Beckwitt's curious campaign to build an underground bunker for protection from a nuclear attack. Michael Kunzelman, Fox News, "Deadly fire exposes wealthy man's secret underground tunnels," 9 Sep. 2018 An official involved in the planning for the visit said there was even discussion of having the president visit the underground London bunker used by Mr. Churchill as a war room during World War II. Katie Rogers, New York Times, "British Roll Out Trump’s Political Idol: Winston Churchill," 12 July 2018 Nantucket officials are considering whether to make a museum out of an underground military bunker that was reportedly built to shelter President John F. Kennedy from a nuclear attack. Emily Sweeney, BostonGlobe.com, "There’s a Cold War-era bunker that was built to shelter President Kennedy on Nantucket," 14 May 2018 Even kids paying no attention to the lessons will find much to like about being in an underground bunker. Scott Craven, azcentral, "Spring break ideas for elementary school kids in Arizona," 9 Mar. 2018

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

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First Known Use of underground

Adverb

14th century, in the meaning defined at sense 1

Noun

1594, in the meaning defined at sense 1

Adjective

1601, in the meaning defined at sense 1

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Last Updated

10 Jan 2019

Look-up Popularity

Time Traveler for underground

The first known use of underground was in the 14th century

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More Definitions for underground

underground

adverb

English Language Learners Definition of underground

 (Entry 1 of 3)

: below the surface of the earth

: in or into a place that is hidden or secret : out of the view of the public

underground

noun

English Language Learners Definition of underground (Entry 2 of 3)

: a system of trains that run below the ground in a large city

the underground : a group of people who secretly work to oppose or overthrow a government

underground

adjective

English Language Learners Definition of underground (Entry 3 of 3)

: located or occurring below the surface of the earth

: secret and usually illegal

: of, relating to, or produced in a social and artistic world that is different and separate from the main part of society

underground

adverb
un·​der·​ground | \ ˌən-dər-ˈgrau̇nd \

Kids Definition of underground

 (Entry 1 of 3)

1 : below the surface of the earth
2 : in or into hiding or secret operation The rebels went underground.

underground

noun
un·​der·​ground | \ ˈən-dər-ˌgrau̇nd \

Kids Definition of underground (Entry 2 of 3)

1 : subway
2 : a secret political movement or group

underground

adjective
un·​der·​ground | \ ˈən-dər-ˌgrau̇nd \

Kids Definition of underground (Entry 3 of 3)

1 : located under the surface of the ground underground pipes
2 : done or happening secretly an underground revolt

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Comments on underground

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