underground

adverb

• beneath the surface of the ground:miners working underground
• in or into secrecy or hiding, especially as a result of carrying out subversive political activities:many were forced to go underground by the government

adjective

• situated beneath the surface of the ground:an underground car park
• relating to or denoting the secret activities of people working to subvert an established order:Czech underground literature
• relating to or denoting a group or movement seeking to explore alternative forms of lifestyle or artistic expression; radical and experimental:the New York underground art scene

noun

• 1 (often the Underground) British an underground railway, especially the one in London:travel chaos on the Underground

• 2a group or movement organized secretly to work against an existing regime: the French underground
• a group or movement seeking to explore alternative forms of lifestyle or artistic expression:the late sixties underground

verb

• lay (cables) below ground level: sections of electricity line had been undergrounded (as noun undergrounding)the environment secretary ordered the undergrounding of cables