The adverb is pronounced ^ndərgraʊnd. The noun and adjective are pronounced ^ndərgraʊnd.
1 adv Something that is underground is below the surface of the ground.
ADV after v
Solid low-level waste will be disposed of deep underground..., The plane hit so hard that one engine was buried 16 feet underground.
Underground is also an adjective., adj ADJ n
...a run-down shopping area with an underground car park., ...underground water pipes.
2 n-sing Theunderground in a city is the railway system in which electric trains travel below the ground in tunnels.
(BRIT) the N, also by N
...a woman alone in the underground waiting for a train..., He crossed London by underground...
in AM, use subway
3 n-sing In a country which is controlled by an enemy or has a harsh government, the underground is an organized group of people who are involved in illegal activities against the people in power.
These US dollars were smuggled into the country during the war, to aid the underground.
4 adj Underground groups and activities are secret because their purpose is to oppose the government and they are illegal.
They are accused of organising and financing an underground youth movement.
5 adv If you go underground, you hide from the authorities or the police because your political ideas or activities are illegal.
ADV after v
After the violent clashes of 1981 they either went underground or left the country.
Translation English Cobuild Collins Dictionary
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