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

Relevance

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

Although the convent was demolished in the 16th century and hundreds of thousands of its bricks were removed, much of its underground footprint survived. — Andrea Margolis, FOXNews.com, 7 Sep. 2026 In the driller's cabin atop the rig, screens display real-time metrics sent back from underground sensors — data that's simultaneously being monitored from company headquarters in Houston. — Pippa Stevens, CNBC, 5 Sep. 2026

Noun

To many, Anthony Bourdain is the patron saint of the culinary underground. — Patrick Ryan, USA Today, 13 Aug. 2026 The frustrations of manufacturing clean hydrogen have convinced many entrepreneurs and scientists to instead seek the element underground. — IEEE Spectrum, 11 Aug. 2026

Adverb

But old-school defenses still matter, too, including obstacles meant to stop tanks and command posts buried underground across the tiny nation. — Aaron MacLean, CBS News, 8 Sep. 2026 After being hidden underground for centuries, its blues and terra cotta colors are still clear but faded. — ABC News, 8 Sep. 2026 See All Example Sentences for underground

Recent Examples of Synonyms for underground

Adjective

Across Greengrass’ three Bourne movies, the elite assassin turns against the clandestine institution that created him, determined to escape its grip and bring its covert operations to light.

— Brian Davids, HollywoodReporter, 10 Sep. 2026
Or that the Apollo moon landing in 1969 was staged, the video shot on some clandestine movie set.

— Susan Page, USA Today, 1 Sep. 2026

Definition of clandestine

Adjective

Scheduled for late 2026, Ceres will drill the world’s first commercial-scale superhot horizontal wells, bringing subterranean power one step closer to the grid.

— Mrigakshi Dixit, Interesting Engineering, 4 Sep. 2026
The Den, a subterranean hangout just down the stairs, feels like the Platonic ideal of hanging out in your parents’ basement, with plenty of seating and a pool and backgammon table to play around on.

— Condé Nast, Condé Nast Traveler, 2 Sep. 2026

Definition of subterranean

Noun

Aside from a matchup with Notre Dame in November, Miami won’t face a ton of resistance on its 2026 schedule (which will be a talking point on several levels over the next few months).

— Dane Brugler, New York Times, 8 Sep. 2026
His persistent claims raised sovereignty concerns and caused resistance from Greenlandic and Danish leaders and heightened tensions among NATO allies.

— Lorne Cook, Los Angeles Times, 7 Sep. 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

Adjective

Two men, ages 89 and 73, were caught with a house full of cocaine, marijuana and guns after Miami police conducted a raid Wednesday afternoon following an undercover sting in August, according to their arrest reports.

— David Goodhue, Miami Herald, 11 Sep. 2026
Jackson was particularly vocal in her criticism of the show’s shallow scripts, which featured plotlines about them going undercover as French maids, showgirls, lifeguards and, perhaps most infamously, prison inmates.

— Michael Callahan, HollywoodReporter, 11 Sep. 2026

Definition of undercover

Adverb

There has been a string of alarming incidents in which swarms of rogue AI agents have hacked online platforms such as Hugging Face and surreptitiously communicated with one another on message boards.

— Sebastian Herrera, Fortune, 14 Sep. 2026
In June, Wilder resident Tyler Cain filed a tort claim against the city, alleging the city’s three Flock Safety cameras were acquired surreptitiously and outside the measure of the law.

— Noah Daly September 2, Idaho Statesman, 2 Sep. 2026

Definition of surreptitiously

Adjective

Across Greengrass’ three Bourne movies, the elite assassin turns against the clandestine institution that created him, determined to escape its grip and bring its covert operations to light.

— Brian Davids, HollywoodReporter, 10 Sep. 2026
Even within those strict parameters, the researchers discovered that about 1,200 AI agents that were not supposed to be communicating with each other used a covert message board.

— Shaun Raviv, CBS News, 10 Sep. 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

Browse Nearby Words

undergraduates

underground

undergrounds

See all Nearby Words

Cite this Entry

Style

“Underground.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/underground. Accessed 17 Sep. 2026.

Copy Citation

Synonyms of underground

adjective

noun

adverb

Example Sentences

Browse Nearby Words

Cite this Entry

More from Merriam-Webster on underground

More from Merriam-Webster

Word of the Day

watershed

Popular in Grammar & Usage

Why do we use apostrophes to show possession?

Merriam-Webster’s Great Big List of Words You Love to Hate

The Exceptions of '-s' and '-es' Plurals

A Who’s Who Regarding ‘Who’s’ and ‘Whose’

'A' or 'an'? What about before 'h'? An Indefinite Article Guide

Popular in Wordplay

9 Words That Sound Like Insults But Aren't

Back to School Vocabulary

Words from the 'Odyssey'

14 Phobias You Probably Haven't Heard Of

12 Lovely and Unusual Words for the Natural World

Popular

Why do we use apostrophes to show possession?

9 Words That Sound Like Insults But Aren't

Back to School Vocabulary

Games & Quizzes