underground

• 指在地面以下的、地下的；也用来形容非主流的、前卫的或秘密的文化、艺术或活动。

Describes something that exists, operates, or is situated beneath the surface of the ground; also used to describe subcultural, avant-garde, or non-mainstream movements.

1. Beneath the earth's surfaceA2formal

   Located, occurring, or operating below the ground level.

   地下的

   • The underground railway system is very efficient in this city.
   • They built an underground bunker for safety.
   • The pipes run through an underground tunnel.

   同义词belowgroundburiedsubsurfacesubterranean

   反义词abovegroundsurface

2. Secret or covertB2formal

   Conducted in a hidden or secretive manner, often outside official or mainstream channels.

   地下的

   • The group operated an underground network to help refugees.
   • He was part of an underground resistance movement during the war.
   • The magazine was distributed through underground channels.

   同义词clandestinecovertfurtivehiddensecretsub rosasurreptitiousundercover

   反义词openovertpublic

• 副词，表示“在地面以下”或“秘密地、暗中地”。可用于具体位置（如地下采矿、地铁），也可用于比喻性的隐秘活动（如地下运动）。

An adverb meaning "beneath the surface of the ground" or "in a hidden or secret manner." It can refer to physical location (e.g., mining, subway) or metaphorical secrecy (e.g., underground movements).

1. Beneath the earth's surfaceA2formal

   Located or moving below the ground level.

   在地下

   • The miners worked underground for hours.
   • Pipes are laid underground to carry water.
   • The subway runs underground through the city center.

2. In secret or hidingB2informal

   Operating or existing in a concealed or clandestine manner, often to avoid detection or authority.

   秘密地

   • The rebels were forced to go underground after the crackdown.
   • The organization operates underground to avoid government surveillance.
   • He lived underground for years to escape persecution.

   同义词covertlyfurtivelyin secretprivatelysecretlystealthilysub rosasurreptitiouslyundercover

   反义词openlyovertlypublicly

• 名词，主要有两个意思：为反抗或推翻当权政府而秘密活动的组织；或指在城市地下运行的电车/铁路系统。

A noun with two primary meanings: a secret organization working to resist or overthrow a ruling power, or an urban electric railway system that runs beneath the ground.

1. Secret resistance movementB2formal

   A covert group organized to oppose or overthrow a government or occupying force.

   地下组织

   • The underground operated in the shadows to sabotage the regime.
   • Members of the underground distributed pamphlets calling for freedom.
   • He joined the underground to fight against the occupation.

   同义词maquisresistance

2. Subway systemA2formalbritish

   An electric railway that runs beneath the surface of the ground, typically in a city.

   地铁

   • We took the underground to get to the city center.
   • The London underground is one of the oldest in the world.
   • She uses the underground every day to commute to work.

   同义词metrosubwaytubeunderground railway