underground
underground — adjective
1. situated in the area below the top layer of the earth.
situated in the area below the top layer of the earth.
The car park is underground, so the cars stay cool in summer.
Work crews are laying underground cables for the new internet network.
collocation: underground cable / underground pipe
Romi heard a low rumbling from an underground river beneath the street.
The building inspector found cracks in the underground drainage pipes.
collocation: underground drainage / underground passage
Moles dig an underground network of tunnels to search for food.
- underground cave
- underground parking
- underground cable
- underground pipe
- underground passage
- subterranean
more formal and scientific; used for natural formations like caves or geological layers
- buried
implies something has been placed or covered under earth, not necessarily a permanent structure
- aboveground
on or above the surface of the earth
- surface-level
at the same level as the ground, not below it
2. carried out in a hidden way, typically because the activity breaks official rule
carried out in a hidden way, typically because the activity breaks official rules or opposes the people in power.
During the war, students printed an underground newspaper that the government had banned.
collocation: underground newspaper / underground magazine
The charity discovered that an underground network was selling fake passports.
Inês took part in underground meetings where activists planned the protest.
collocation: underground meeting / underground movement
Police raided an underground casino that had been operating for years without a licence.
The regime tried to silence all underground political activity in the region.
collocation: underground activity / underground political activity
- underground newspaper
- underground movement
- underground network
- underground activity
- underground meeting
- clandestine
more formal and dramatic, often used in espionage or military contexts
- covert
suggests official secrecy by a government or agency; not necessarily illegal
- illicit
focuses on the illegal nature of the activity rather than the secrecy
- official
approved by those in authority; not hidden
- aboveboard
completely open and honest, with nothing hidden
Usage Note
Frequently used before nouns describing media, organizations, or political actions that operate outside official permission.
Common Mistakes
3. relating to the secret network of safe houses and helpers in 19th-century Americ
relating to the secret network of safe houses and helpers in 19th-century America that guided enslaved African Americans to freedom in northern states or Canada.
Harriet Tubman is the most famous conductor on the Underground Railroad.
proper noun: the Underground Railroad
The museum exhibit shows the underground escape routes used before the Civil War.
Ezra led a group of twelve escaped slaves through the woods to a safe house in Pennsylvania.
concrete historical scene: conductor leading escaped slaves to a safe house
James's great-great-grandmother was hidden by an underground station in Ohio in 1859.
Local historians are mapping the underground safe houses that once dotted the countryside.
collocation: underground safe house / underground station
- Underground Railroad
- underground network
- underground route
- underground station
- underground safe house
Usage Note
Almost always used with 'Railroad' or in explicit historical contexts. Outside US history, this sense does not apply.
Common Mistakes
underground — noun
1. a city passenger train system whose trains run mostly through tunnels beneath th
a city passenger train system whose trains run mostly through tunnels beneath the streets.
Tariq takes the underground to work every morning because it is faster than driving.
pattern: take the underground
The London underground is one of the oldest metro systems in the world.
The ticket machine at the underground station was not working this morning.
collocation: underground station
A map of the underground is posted at every entrance to the platform.
During rush hour the underground trains are packed with commuters.
collocation: underground train
- the underground
- underground station
- underground train
- underground map
- take the underground
Grammar Patterns
the underground
Usage Note
Typically used with the definite article ('the underground'). In American English, 'subway' is the common equivalent; in many other cities, 'metro' is used.
Common Mistakes
2. the people and groups who reject mainstream society's values and produce art, mu
the people and groups who reject mainstream society's values and produce art, music, or lifestyles that are unconventional or deliberately provocative.
The punk rock underground of the 1970s changed fashion and music forever.
collocation: [genre] underground — e.g. punk underground, art underground
Hyun's photography was noticed by the New York art underground for its raw style.
Zines from the feminist underground of the 1990s are now collected by university libraries.
The underground in Berlin has always attracted musicians who dislike commercial pop music.
Sirin's band started in the local underground and later signed with a major record label.
pattern: the local underground
- the art underground
- the music underground
- the political underground
- the local underground
- the underground scene
- avant-garde
focuses on artistic innovation rather than cultural opposition; often narrower in scope
- counterculture
broader term for a whole way of life opposed to mainstream norms, not limited to art
- the alternative scene
more informal; refers to music, fashion, and lifestyle choices outside the mainstream
- the establishment
the dominant social group that holds power and authority
- the mainstream
the prevailing cultural trends accepted by the majority of people
Grammar Patterns
the underground
Usage Note
Used with 'the' and often preceded by a modifier like 'artistic', 'musical', 'political', or a place name ('London underground scene'). The reference is to a collective, not specific individuals.
Common Mistakes
3. an organization that works in secret to challenge a ruling power or foreign mili
an organization that works in secret to challenge a ruling power or foreign military controlling their land.
Members of the French underground helped Allied pilots escape from Nazi-occupied territory.
proper noun: the French underground
Vikram's grandfather joined the underground after the invasion and printed anti-government pamphlets.
The underground supplied food and medicine to families trapped in the war zone.
When the dictator fell, former underground leaders formed the new government.
collocation: underground leader
The resistance underground used secret codes to communicate between safe houses.
- the French underground
- the resistance underground
- underground leader
- underground fighter
- join the underground
- resistance
more general term; can be public or secret, armed or unarmed
- the resistance movement
more formal and specific, often used in historical writing
- partisans
specifically armed resistance fighters, usually in wartime
- the Maquis
the French rural resistance groups during World War II; very specific context
- the government
the ruling authority that the underground opposes
- the occupying forces
the foreign military presence that the underground fights against
Grammar Patterns
the underground
Usage Note
Typically preceded by 'the' and often modified by a nationality or region ('the Polish underground'). Distinguished from sense 2 (COUNTERCULTURE) by its focus on political/military opposition rather than artistic or lifestyle rebellion.
Common Mistakes
underground — adverb
1. in the area that lies below the planet's surface.
in the area that lies below the planet's surface.
The rabbits burrowed underground to build their nest away from predators.
Chidi works underground in a gold mine near Johannesburg.
collocation: work underground / mine underground
During the storm, the power lines were moved underground to prevent damage.
pattern: move [something] underground
The pipes run underground from the reservoir to each house in the village.
Nuclear waste is stored deep underground in special containers.
collocation: deep underground / buried underground
- buried underground
- go underground
- run underground
- deep underground
- move underground
- below ground
slightly more formal, often used in technical or construction contexts
- beneath the surface
more descriptive; can be used literally or figuratively
- aboveground
on or above the surface of the earth
Grammar Patterns
verb + underground
Usage Note
Often follows verbs of movement or placement (go, burrow, run, store, bury, move). Typical position is immediately after the verb or at the end of the clause.
Common Mistakes
2. into a situation where one's actions or whereabouts are hidden from the authorit
into a situation where one's actions or whereabouts are hidden from the authorities or the public.
After the warrant was issued, the suspect went underground and changed his identity.
pattern: go underground (most common)
The opposition party was forced underground after the coup.
pattern: forced underground
Tamar lived underground for two years before the authorities finally caught her.
Many activists drove underground when the new surveillance law took effect.
The journalist had to stay underground after publishing the leaked documents.
pattern: stay underground
- go underground
- forced underground
- driven underground
- stay underground
- live underground
- into hiding
broader; can be for any reason (fear, shame, danger), not necessarily political
- off the grid
modern informal term; implies avoiding digital surveillance rather than physical hiding
- in the shadows
more literary; suggests operating secretly while remaining in public view
- into the open
into public visibility; ceasing to hide
- above board
openly and legally
Grammar Patterns
go underground
drive underground
force underground
Usage Note
Most commonly appears in the fixed expression 'go underground'. Also used with verbs like 'force', 'drive', 'stay', 'live'. The sense is always about evasion from authority, not literal physical location.
Common Mistakes
Word family
- undergroundernounC1
Synonym discussion
Sense: noun/1
All four words refer to an urban passenger railway system that runs mostly in tunnels, but each belongs to a different regional variety. 'Underground' (often capitalised as 'the Underground') is the standard British term, best known from the London Underground, and is also used in some other English-speaking countries such as India and South Africa. 'Subway' is the dominant term in American and Canadian English ('the New York subway'). 'Tube' is an informal, specifically British nickname for the London Underground, derived from the shape of its deep-level tunnels. 'Metro' is the common term in many European and Asian cities (Paris, Moscow, Beijing, Washington D.C.) and is increasingly used internationally as a neutral, non-regional descriptor. When giving directions to a tourist, use the local term: 'Take the Tube in London, the Subway in New York, and the Metro in Paris.'
Common collocations
Nouns
- underground system
- underground network
- underground movement
Adverbs
- deep underground
- far underground
- completely underground
Phrases
- the underground
- go underground
Etymology
Formed by combining the Old English words 'under' (beneath) and 'grund' (bottom, foundation, ground). The literal meaning 'below the ground' has existed since the 1300s. The figurative sense of 'secret, hidden from authorities' emerged in the 1600s, originally referring to hidden political or religious groups. The noun use for an underground railway dates from the late 1800s, when the London Underground opened in 1863 as the world's first subway system.