I. un ‧ der ‧ ground 1 /ˈʌndəɡraʊnd $ -ər-/ BrE AmE adjective
[ Word Family: noun : ↑ ground , ↑ underground , ↑ grounding , GROUNDS ; adjective : goundless, ↑ underground ≠ ↑ overground , ↑ grounded ; verb : ↑ ground ; adverb : ↑ underground ]
1 . below the surface of the earth:
an underground passage
The car park is underground.
2 . [only before noun] an underground group, organization etc is secret and illegal:
an underground terrorist organization
3 . [only before noun] underground literature, newspapers etc are read by a small number of people, and would seem slightly strange or shocking to most people:
the underground press
• • •
THESAURUS
▪ secret known about by only a few people, who have agreed not to tell anyone else:
a secret meeting place
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The details of the proposal must remain secret.
▪ confidential used about information, especially in business or government, that is secret and not intended to be shown or told to other people:
a highly confidential report
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Employees’ personal details are treated as strictly confidential.
▪ classified used about information that the government has ordered to be kept secret from most people:
He was accused of passing on classified information to the Russians in the 1950s.
▪ sensitive used about information that is kept secret because there would be problems if the wrong people knew it:
A teenager managed to hack into sensitive US Air Force files.
▪ covert [only before noun] used about things that are done secretly, especially by a government or official organization:
a CIA covert operation
▪ undercover [usually before noun] used about things that are done secretly by the police in order to catch criminals or find out information:
Detectives arrested the suspect after a five-day undercover operation.
▪ underground an underground organization or newspaper is one that operates or is produced secretly and opposes the government:
Her father was a member of the underground resistance movement in France during World War II.
▪ clandestine /klænˈdestən, klænˈdestɪn/ secret and often illegal or immoral:
clandestine meetings
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his involvement in a clandestine operation to sell arms to Iran
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a clandestine love affair
▪ hush-hush informal used about information or activities that are kept officially secret:
He was put in charge of some hush-hush military project.
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I’ve no idea what he does – it’s all very hush-hush.
II. un ‧ der ‧ ground 2 /ˌʌndəˈɡraʊnd $ -ər-/ BrE AmE adverb
[ Word Family: noun : ↑ ground , ↑ underground , ↑ grounding , GROUNDS ; adjective : goundless, ↑ underground ≠ ↑ overground , ↑ grounded ; verb : ↑ ground ; adverb : ↑ underground ]
1 . under the earth’s surface:
This animal spends most of its life underground.
nuclear waste buried deep underground
2 . go underground to start doing something secretly, or hide in a secret place:
The ANC was forced to go underground when its leaders were arrested.
III. un ‧ der ‧ ground 3 /ˈʌndəɡraʊnd $ -ər-/ BrE AmE noun
[ Word Family: noun : ↑ ground , ↑ underground , ↑ grounding , GROUNDS ; adjective : goundless, ↑ underground ≠ ↑ overground , ↑ grounded ; verb : ↑ ground ; adverb : ↑ underground ]
the Underground
a) British English a railway system under the ground SYN subway American English
b) an illegal group working in secret against the rulers of a country