English Reference
adjective · adverb · noun

underground

adj. · adv. · n.
US /ˈəndɝˌɡɹaʊnd/ un·der·ground UK spelling undergrounds

  1. 01 A2 Elementary

    adj.located or happening under the ground.

    adj.situated, occurring, or operating below the surface of the earth.

    Simple

    The hotel has an underground car park for its guests.

    In context

    The engineers discovered an extensive network of underground streams that complicated the foundation work for the new skyscraper.

  2. 02 B2 Upper Intermediate

    adj.secret or outside of the mainstream, often used for art, music, or politics.

    adj.relating to a subculture or movement that is unofficial, non-mainstream, or hidden from authorities.

    Simple

    He plays guitar in an underground rock band that only performs in small clubs.

    In context

    The underground press played a crucial role in distributing information during the years of strict government censorship.

  3. 03 A2 Elementary

    adv.under the surface of the earth.

    adv.below the surface of the ground; in or into a subterranean location.

    Simple

    Rabbits live underground in tunnels called burrows.

    In context

    The utility company decided to move all the power lines underground to protect them from severe winter storms.

    belowground
  4. 04 B2 Upper Intermediate

    adv.into a place or state of hiding to avoid being caught.

    adv.into a state of secrecy or concealment, typically to evade observation or arrest.

    Simple

    The political leader went underground after the police started looking for him.

    In context

    After the failed coup, the remaining activists went underground to reorganise their movement without fear of immediate detection.

    into hidingsecretly
  5. 05 A2 Elementary British English

    n.a railway system that runs under the ground in a city.

    n.an electric passenger railway system operating in tunnels beneath a city surface.

    Simple

    It is much faster to take the underground than to drive through the city centre.

    In context

    The London Underground is the oldest subterranean railway network in the world, with some sections dating back to 1863.

    Usage

    Often used with the definite article 'the'.

    Teacher's tip

    In the UK, people say 'the Underground' or 'the Tube'; in the US, 'the subway' is the standard term.

  6. 06 C1 Advanced Formal

    n.a secret group of people working together to fight against a government.

    n.a clandestine organisation or movement engaged in resisting an established government or occupying power.

    Simple

    She joined the underground to help fight for her country's freedom.

    In context

    Members of the French underground risked their lives to gather intelligence and sabotage enemy supply lines during the occupation.

    Usage

    Usually used with the definite article 'the'.


Etymology 1

From Middle English undergrounde (adverb), equivalent to under + ground or under- + ground. Compare Dutch ondergrond, ondergronds, German Untergrund, Danish undergrunds.

Etymology 2

See the etymology of the corresponding lemma form.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin Middle English undergrounde
Level A2 · Elementary
Frequency Common
Updated