underground

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.

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

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

A2 · Elementary

adv. under the surface of the earth.

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

“Rabbits live underground in tunnels called burrows.”

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

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.

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

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

A2 · Elementary Countable noun 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.

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

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

C1 · Advanced Countable noun 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.

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

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