UNDERGROUND Synonyms: 83 Similar and Opposite Words

underground 1 of 3

adjective

ˈən-dər-ˌgrau̇nd

Definition of underground

as in clandestine

undertaken or done so as to escape being observed or known by others an underground operation to smuggle ancient artifacts out of the country

Synonyms & Similar Words

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Antonyms & Near Antonyms

as in subterranean

being, situated, or operating beneath the surface of the earth an underground shopping mall that is part of the city's subway system

Synonyms & Similar Words

Antonyms & Near Antonyms

underground

2 of 3

noun

ˈən-dər-ˌgrau̇nd

as in resistance

a secret organization in a conquered country fighting against enemy forces joined the underground while still a teenager

Synonyms & Similar Words

underground

3 of 3

adverb

as in undercover

Related Words

Dissimilar Words

Example Sentences

Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.

Recent Examples of underground

Adjective

Beijing maintains strict controls over religion, which has led to the rise of underground churches. — J.d. Capelouto, semafor.com, 5 July 2026 The Zion Church is among the largest underground or house churches in China that are unregistered with authorities. — Didi Tang, Los Angeles Times, 5 July 2026

Noun

When oil wells are shut in, the pressure underground can become imbalanced, deforming the underlying structure. — David Goldman, CNN Money, 24 June 2026 The company now plans to demonstrate commercial-scale borehole drilling before attempting deployment of a prototype reactor underground. — Aamir Khollam, Interesting Engineering, 24 June 2026

Adverb

In addition, the owners added a gas line for the appliances and moved the electrical feed underground. — James Alexander, Hartford Courant, 5 July 2026 Now, that excess gets diverted into the Austerlitz basin instead, where it’s held deep underground until the weather clears, then pumped gradually to treatment plants outside the city. — Camille Knight, CNN Money, 4 July 2026 See All Example Sentences for underground

Recent Examples of Synonyms for underground

Adjective

That the actual, original Antifa formed in clandestine resistance to Nazi terror during the early 1930s appears lost amid the rhetorical vagaries of political propaganda.

— Ara H. Merjian, ARTnews.com, 10 July 2026
Russia and China are seeking the capability to disable and eventually destroy Elon Musk’s Starlink satellite network, an investigation found, as the allies deepen their clandestine military cooperation.

— Brendan Ruberry, semafor.com, 9 July 2026

Definition of clandestine

Adjective

Visitors to the park can enjoy surface and subterranean exploration, canoeing the Green River, hiking, camping, and horseback riding.

— Josh Laskin, Travel + Leisure, 3 July 2026
The spa There’s a dreamy subterranean spa with all the standard treatments, but to really get into Potato Head’s groove, opt for a session at the New Age-y Sanctuary Wellness Centre instead.

— Condé Nast, Condé Nast Traveler, 1 July 2026

Definition of subterranean

Noun

With more than 2,000 excess deaths recorded over six days at the peak of the June heat, according to health authorities, France’s cultural resistance to AC has started to soften.

— CNN Money, CNN Money, 7 July 2026
Why photonics matters Unlike electrical signals, which encounter increasing resistance and power losses as data rates climb, optical communication can transmit enormous amounts of information with significantly lower energy consumption.

— Kaif Shaikh, Interesting Engineering, 6 July 2026

Definition of resistance

Adverb

The noble consort takes the empress’s place, smirking, and stealthily pushes her down the stairs when no one is watching.

— Lavender Au, The Dial, 30 June 2026
But did Spilotro go about life as an upstanding model citizen who rubbed elbows with the Vegas elite, while quietly and stealthily protecting the Mafia's financial interests in Vegas casinos?

— Adam Harrington, CBS News, 23 June 2026

Definition of stealthily

Adjective

Duties include developing operation plans and going undercover.

— Sacbee.com, Sacbee.com, 7 July 2026
In exchange, one of the agents asked Lumumba to move the city’s deadline for the hotel project from April 30 to April 10 or 15, giving the undercover FBI agents an advantage over other developers.

— Natalie Neysa Alund, USA Today, 6 July 2026

Definition of undercover

Adverb

Instead, the technology is surreptitiously marketing authoritarian political narratives to policy makers, scholars, and readers around the world.

— Michael Schuman, The Atlantic, 7 July 2026
As a group of dancers surrounded her on the B-stage, she was surreptitiously harnessed into a rig that carried her aloft, limp yet belting, into the heavens, or at least into what looked like a UFO hovering over the arena.

— Chris Willman, Variety, 7 June 2026

Definition of surreptitiously

Adjective

Lioness stars Nicole Kidman, Zoe Saldaña, and Morgan Freeman, and follows an all-female CIA team known as the Lionesses, who conduct covert missions in the War on Terror.

— Brianna Zigler, Entertainment Weekly, 7 July 2026
Since Russian President Vladimir Putin launched his full-scale invasion in 2022, following his covert invasions of Ukraine’s Crimean peninsula and eastern regions in 2014, Russian forces have captured roughly 12% of Ukraine’s territory.

— Los Angeles Times, Los Angeles Times, 6 July 2026

Definition of covert

Adverb

Soon afterward, social media commenters were speculating about whether Sierra broke into the office or was caught clandestinely shredding documents.

— Don Stacom, Hartford Courant, 10 July 2026
This great disparity between reality and story, truth and history, takes on new dimensions when Robin clandestinely takes refuge at an island priory where Sister Brigid (Jodie Comer) tends to his wounds.

— ABC News, ABC News, 17 June 2026

Definition of clandestinely

Browse Nearby Words

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“Underground.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/underground. Accessed 12 Jul. 2026.

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Synonyms of underground

adjective

noun

adverb

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