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

In other words, the atmosphere becomes enriched by material from underground, while also becoming depleted in some gases that astronomers would expect to see in greater abundance. — Keith Cooper, Space.com, 13 July 2026 Oncor will be upgrading critical underground electric infrastructure to improve service reliability and reduce future outage risks for customers in Dallas. — Briseida Holguin, CBS News, 13 July 2026

Noun

Invisible hands strap her legs onto the stirrups, an iron fist plunging her through a tunneling, gravity‑bending, black underground. — Literary Hub, 25 June 2026 When oil wells are shut in, the pressure underground can become imbalanced, deforming the underlying structure. — David Goldman, CNN Money, 24 June 2026

Adverb

Three 55-gallon drums and other debris were buried underground. — Sacbee.com, 8 July 2026 Rather than choosing between unrestricted gray-market access or a blanket crackdown that simply drives use underground, the agency can chart a third way on peptides. — Jerome Adams, STAT, 6 July 2026 See All Example Sentences for underground

Recent Examples of Synonyms for underground

Adjective

Attorney Cynthia Jennings, who spoke at a press conference called several days after the police were at the treasurer’s office, had condemned social media speculation about Sierra’s action and the claims of clandestine shredding of documents.

— Helen I. Bennett, Hartford Courant, 17 July 2026
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

Definition of clandestine

Adjective

Call it the canary yellow uniforms in the coal mine — except the Red Sox have shot up the elevator shaft, bursting from their subterranean crypt.

— Tyler Kepner, New York Times, 20 July 2026
The winding, dry riverbeds are dotted with massive Ana trees, whose roots dive 98 to 130 feet deep into hidden subterranean water.

— Rebekah Peppler, Travel + Leisure, 14 July 2026

Definition of subterranean

Noun

The collective leadership that has emerged in the absence of Khamenei’s son Mojtaba, the new supreme leader, appears to believe that resistance is the only option for now.

— Tim Lister, CNN Money, 20 July 2026
Targeting the hardest waste – plastic With global plastic production now exceeding 460 million tonnes annually, the material’s extreme resistance to degradation has raised serious environmental concerns.

— Mrigakshi Dixit, Interesting Engineering, 20 July 2026

Definition of resistance

Adverb

Damon can be as crisp an orator as any actor now working, but his performance here reminds you why Jason Bourne, moving stealthily through a crowd like a sheathed dagger, remains one of his defining roles.

— Justin Chang, New Yorker, 17 July 2026
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

Definition of stealthily

Adjective

The complaint was the result of a months-long investigation in which undercover operators posed as prospective tenants and recorded phone calls with Greystar employees to test their compliance with the law.

— Jack Flemming, Los Angeles Times, 15 July 2026
The Chicago Police Department also carries out undercover stings at small massage parlors after the city receives complaints of vice activity.

— Sam Charles, Chicago Tribune, 13 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

These functions can be critical in various applications and scenarios, such as inspections, covert surveillance, search-and-rescue operations, disaster monitoring, and agricultural pest tracking.

— New Atlas, New Atlas, 18 July 2026
Although, with words like emergency and bunker—the skeptics have made routine election work seem like a covert-ops thriller.

— Hanna Rosin, The Atlantic, 16 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

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 21 Jul. 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

dog days

Popular in Grammar & Usage

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

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

Do you 'say your piece' or 'say your peace'?

Why is '-ed' sometimes pronounced at the end of a word?

Commonly Misspelled Words

Popular in Wordplay

14 Phobias You Probably Haven't Heard Of

It's a Scorcher! Words for the Summer Heat

The Longest Long Words List

Ten Words Ending with a Silent ‘T’

Why do we say 'fly off the handle'?

Popular

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

14 Phobias You Probably Haven't Heard Of

It's a Scorcher! Words for the Summer Heat

Games & Quizzes