adv
noun
adj
Freq #3145
Meanings
-
1
adj
Below the surface of the ground.
There is an underground tunnel that goes across the river.
-
2
adv
Below the surface of the ground.
The pipes run underground for several miles.
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3
noun
A city railway system that runs below the ground.
In London the train system is called the underground.
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4
adj
Secret or hidden, especially from the authorities.
These criminals operate through an underground network.
Thesaurus
Synonyms
1
adj
· below the surface of the...
subterranean
2
adv
· below the surface of the...
below ground
Word family
Forms
undergrounds
Common collocations
Etymology
From Middle English undergrounde (adverb), equivalent to under + ground or under- + ground. Compare Dutch ondergrond, ondergronds, German Untergrund, Danish undergrunds.
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