■ adjective & adverb
1》 beneath the surface of the ground.
2》 in secrecy or hiding, especially as a result of carrying out subversive political activities.
3》 seeking to explore alternative forms of lifestyle or artistic expression; radical and experimental.
■ noun
1》 (often the Underground ) Brit. an ~ railway, especially the one in London.
2》 a group or movement organized secretly to work against an existing regime.
3》 a group or movement seeking to explore alternative forms of lifestyle or artistic expression.