1
- beneath the surface of the ground在地下：
miners working underground.
地下作业的矿工。
1.1
- in or into secrecy or hiding, especially as a result of carrying out subversive political activities（尤指从事颠覆活动）秘密地, 不公开地：
many were forced to go underground by the government.
政府使许多人被迫转入地下活动。
1
- situated beneath the surface of the ground位于地下的：
an underground car park.
地下停车场。
1.1
- of or relating to the secret activities of people working to subvert an established order秘密的, 地下的：
Czech underground literature.
捷克地下文学。
1.2
- of or denoting a group or movement seeking to explore alternative forms of lifestyle or artistic expression; radical and experimental先锋派的; 急进探索的：
the New York underground art scene.
纽约先锋艺术景观。
1
- （常作the Underground）Brit. an underground railway, especially the one in London〈英〉（尤指伦敦）地铁：
travel chaos on the Underground.
地铁运营混乱
he'd gone home by underground.
他已乘地铁回家。
2
- a group or movement organized secretly to work against an existing regime（反对现有政权的）地下组织或运动。
2.1
- a group or movement seeking to explore alternative forms of lifestyle or artistic expression先锋派组织或运动：
the late sixties underground.
六十年代后期的先锋派运动。