[only before noun] an underground group, organization etc is secret and illegal
〔组织、机构等〕地下的，秘密的，不合法的:
【例句】
an underground terrorist organization
秘密恐怖主义组织
3.
【释义】
[only before noun] underground literature, newspapers etc are read by a small number of people, and would seem slightly strange or shocking to most people
〔文学作品、报纸等〕地下的:
【例句】
the underground press
地下报刊
adverb
1.
【释义】
under the earth's surface
在地（面）下:
【例句】
This animal spends most of its life underground.
这种动物一生中的大部分时间都呆在地下。
【例句】
nuclear waste buried deep underground
深埋在地下的核废料
2.
【释义】
go underground, to start doing something secretly, or hide in a secret place
转入地下; 隐匿:
【例句】
The ANC was forced to go underground when its leaders were arrested.
领导人被捕之后，非洲国民大会被迫转入地下。
noun
1.
【释义】
the Underground
1.1
【释义】
[BrE] a railway system under the ground
地下铁路，地铁;
1.2
【释义】
an illegal group working in secret against the rulers of a country
