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

The result was the equivalent of an X-ray of the subsurface extending roughly 300 feet underground, without drilling a single hole. — Nolan Roth, Scientific American, 23 Aug. 2026 Once an extensive underground network of rhizomes develops, Messinger explains that complete removal becomes considerably more difficult. — Sj McShane, Martha Stewart, 23 Aug. 2026

Noun

The frustrations of manufacturing clean hydrogen have convinced many entrepreneurs and scientists to instead seek the element underground. — IEEE Spectrum, 11 Aug. 2026 Born William Wainwright in north London in 1956, Orbit left school at 16 and immersed himself in the city’s post-punk underground. — Spin Staff, SPIN, 7 Aug. 2026

Adverb

For decades, energy geologists thought hydrogen molecules were too small and light to stay trapped underground without leaking away. — Aman Tripathi, Interesting Engineering, 20 Aug. 2026 And in their relationship with fungi there is more still, underground. — Literary Hub, 20 Aug. 2026 See All Example Sentences for underground

Recent Examples of Synonyms for underground

Adjective

The clandestine manner in which LG monitors were installing ad-pushing software onto third-party devices, however, remains seriously concerning.

— Scharon Harding, ArsTechnica, 24 Aug. 2026
The clandestine transits have changed the game for the Middle Eastern oil industry.

— David Goldman, CNN Money, 22 Aug. 2026

Definition of clandestine

Adjective

Seven bedrooms and eight bathrooms are alongside two bars, a screening room, a 55-foot infinity pool, a sports court, putting greens, and a 10-car subterranean garage.

— Demetrius Simms, Robb Report, 25 Aug. 2026
With its four subterranean levels and three wings, even Calatrava fans admit the space can be overwhelming and difficult to navigate.

— Anne Kadet, Curbed, 24 Aug. 2026

Definition of subterranean

Noun

Art and activism in Cuba In 2013, the artist began following the activism of the Ladies in White, the mothers and wives of political prisoners in Cuba, who have become a symbol of peaceful resistance to the dictatorship by processing to Sunday mass.

— Sarah Moreno, Miami Herald, 31 Aug. 2026
Scientists with the Forest Service and The Nature Conservancy Vermont spent the summer injecting 6,000 young elm trees with Dutch elm disease spores to test their resistance to the disease.

— ABC News, ABC News, 31 Aug. 2026

Definition of resistance

Adverb

Wolf’s Shinobi Prosthetic houses a grappling hook for scaling rooftops, leaping between trees, and approaching enemies stealthily.

— Aman Kumar, Encyclopedia Britannica, 27 Aug. 2026
From there, the group could stealthily disperse the new strain through air-handling systems at major livestock farms across the United States.

— Elizabeth Sherwood-Randall, Foreign Affairs, 18 Aug. 2026

Definition of stealthily

Adverb

Right now, there are no indications exploits are being used to install anything other than Monero miners, which surreptitiously harness a Mac’s resources to perform mathematical operations that generate the cryptocurrency for the attacker.

— Dan Goodin, ArsTechnica, 14 Aug. 2026
That's not the first time a president surreptitiously switched planes.

— Phaedra Trethan, USA Today, 11 Aug. 2026

Definition of surreptitiously

Adjective

Psyops can be overt or covert, but they’re designed with a clear objective, said Jan Goldman, a professor of intelligence and security studies at The Citadel who has also worked on psyops.

— Harmeet Kaur, CNN Money, 27 Aug. 2026
In a recent presentation, OpenAI researchers described how AI agents used a covert message board to plan their next moves.

— Alex Heath, Time, 26 Aug. 2026

Definition of covert

Adverb

Because Iran is a theocratic dictatorship that routinely arrests and in some cases executes journalists, Western reporters hoping to cover the country must either work clandestinely or submit to government supervision.

— James Kirchick, The Atlantic, 29 July 2026
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

Definition of clandestinely

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undergraduates

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“Underground.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/underground. Accessed 1 Sep. 2026.

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Synonyms of underground

adjective

noun

adverb

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