underground 1 of 3

adjective

ˈən-dər-ˌgrau̇nd How to pronounce underground (audio)
Definition of undergroundnext
1
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
2
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 How to pronounce underground (audio)
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
Outer shell will stay underground The double-layer structure is designed to simplify the machine’s recovery after tunneling. — Sujita Sinha, Interesting Engineering, 31 Aug. 2026 As a biography on Allmusic notes, the tapes gained traction in underground circles and the duo eventually signed to a British indie label, which released Half Japanese’s debut album, 1/2 Gentlemen/Not Beasts, in 1980. — Jon Blistein, Rolling Stone, 31 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
Video shows the group, wearing overalls, pulling themselves out from underground and running away. — Amethyst Martinez, USA Today, 24 Aug. 2026 While riding the New York subway, Hariri-Kia’s car stopped underground. — Ct Jones, Rolling Stone, 21 Aug. 2026 See All Example Sentences for underground
Recent Examples of Synonyms for underground
  1. clandestine
  2. subterranean
  3. resistance
  4. stealthily
  5. undercover
  6. surreptitiously
  7. covert
  8. clandestinely
Adjective
  • 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
  • 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
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
  • 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
Adjective
  • And in 1963, Steinem gained national attention for going undercover at one of Hugh Hefner's nightclubs.
    — Juliana Kim, NPR, 3 Sep. 2026
  • The rest of the officers at the Pinellas County Sheriff's Office who were part of setting this undercover operation up and didn’t listen owe the officer an apology.
    — Sean Joseph OutKick, FOXNews.com, 2 Sep. 2026
Definition of undercover
Adverb
  • These malicious apps can be surreptitiously installed by remote attackers even when the devices are positioned behind a router.
    — Dan Goodin, ArsTechnica, 31 Aug. 2026
  • For every song ingested into these LLMs, ALL of the creative elements that went into the track have been surreptitiously appropriated.
    — David Barber, HollywoodReporter, 31 Aug. 2026
Definition of surreptitiously
Adjective
  • Over the last decade, covert tests have revealed vulnerabilities at security checkpoints, with one in 2015 showing a nearly 96% failure rate at screening fake explosives.
    — Kathleen Wong, USA Today, 3 Sep. 2026
  • The film imagines a colorful, family-friendly realm concealed just under the surface of video games themselves, populated by a covert guild of guardians tasked with keeping each title operating and preserving every player’s journey.
    — Naman Ramachandran, Variety, 1 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

“Underground.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/underground. Accessed 8 Sep. 2026.

Copy Citation

More from Merriam-Webster on underground

Britannica.com: Encyclopedia article about underground

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Popular in Grammar & Usage

See More

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

A List of Most Commonly Confused Words

Why do we use apostrophes to show possession?

Is it 'nerve-racking' or 'nerve-wracking'?

What's the difference between 'fascism' and 'socialism'?
See More

Popular in Wordplay

See More

The Longest Long Words List

Stay Woke

Ye Olde Nincompoop: Old-Fashioned Words for 'Stupid'

14 Phobias You Probably Haven't Heard Of

The Words of the Week - Sept. 4
See More

Popular

See More

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

The Longest Long Words List

Stay Woke
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
The Missing Letter A daily crossword with a twist
anagrams on a chalk board
Word Builder Quiz Vol. 2 Pick the letter that when added to a word will ma...
See All