undercoverun‧der‧cov‧er /ˌʌndəˈkʌvə◂ $ -dərˈkʌvər◂/ adjective [only before noun] 
an undercover investigationundercover policeman/cop/agent etc undercover detectives► see thesaurus at secret—undercover adverb: a cop who goes undercover to catch drug dealers He worked undercover in Germany and Northern Ireland.
EXAMPLES FROM OTHER DICTIONARIES
- an undercover investigation
- He was arrested after trying to sell guns to an undercover FBI agent.
- People dived aside as undercover cops ambushed a planned post office raid.
- Six members of a drug-smuggling gang were arrested after an 18-month undercover police operation.
- The unit is equipped to deal with a variety of situations, including undercover surveillance.
- How about undercover angels dressed as Batman and Robin?
- However, the two men he approached to arrange the murder were undercover detectives and Taylor and his daughter were arrested.
- I want to apply to become an undercover agent.
- In a rare public statement, the tough undercover soldiers - whose motto is Who Dares Wins - have apologised.
- One final question seems pertinent: What would the response have been had Mr Brettell's offence involved instead an undercover policewoman?
- Then I heard the slap-slap-slap of rubber-soled feet coming across the yard and did what any ice-cool undercover dude would do.
THESAURUS
known about by only a few people, who have agreed not to tell anyone else: · a secret meeting place· The details of the proposal must remain secret.
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· Employees’ personal details are treated as strictly confidential.
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.
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.
[only before noun] used about things that are done secretly, especially by a government or official organization: · a CIA covert operation
[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.
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.
secret and often illegal or immoral: · clandestine meetings· his involvement in a clandestine operation to sell arms to Iran· a clandestine love affair
informal used about information or activities that are kept officially secret: · He was put in charge of some hush-hush military project.· I’ve no idea what he does – it’s all very hush-hush.
Longman Language Activatorsecret information/plans/places/activities if something is secret , not many people know about it, and they agree not to tell anyone else about it: · The letter was written in a secret code.· Secret documents containing details of Britain's defence plans have been stolen.· The president's schedule is secret, but there is speculation that he will visit UN troops in the area.remain/stay secret: · I hope you see how vital it is that our conversation remains secret.top secret (=when an official document, piece of information etc is very secret): · The experiments were top secret.secret ballot (=a secret vote): · The Leader of the House will be selected by secret ballot.
confidential information is known only by a few official people, and must not be told to anyone else, for example because it contains military secrets or private details about people: · We hold confidential records on each employee.· Always protect confidential files by locking them with a password.· An employee secretly gave confidential memos to the press.highly confidential (=very confidential): · The information we received is of a highly confidential nature and relates to national security.
classified information or documents are ones that the government has ordered to be kept secret: · There is evidence that Huang had access to classified information.· Only licensed companies are eligible to receive, store, or send classified material.
information or documents that are sensitive are likely to cause problems or embarrassment if they are made public and therefore they are kept secret: · A teenager used his personal computer to break into sensitive US Air Force files. · Your competitors may have access to the company intranet, so never discuss commercially sensitive issues on-line.highly sensitive: · The minister admitted that highly sensitive documents had been leaked to the press.
done secretly, especially by a government or official organization, often involving breaking the law: · The chief investigator resigned, amid allegations of covert and probably illegal operations.· The abuse of residents in the home was confirmed by covert video surveillance.
working secretly - use this about the activities of the police, the army etc: · Six members of a drug-smuggling gang were arrested after an 18-month undercover police operation.· The unit is equipped to deal with a variety of situations, including undercover surveillance.
if something is veiled , cloaked , or shrouded in secrecy , very little is known about it and it seems very mysterious: · In Japan, the private lives of the Emperor and his family were once veiled in secrecy.· The President's exact itinerary was cloaked in secrecy for security reasons.· This ground-breaking work is shrouded in secrecy on the instruction of the company's lawyers.
informal kept officially secret: · His death was really hush-hush. It was so covered up that you wondered if it wasn't a suicide.· 'The Manhattan Project' was the insiders' name for the hush-hush project.
use this about methods and activities that involve a lot of secrecy, especially when this seems unnecessary: · He was arrested after a cloak-and-dagger operation involving the CIA and MI6.
secret organizations and people who do secret work: secret police/agent/society etc · She was kept under surveillance by the secret police for over three years.· The film tells the story of a Swiss secret agent who masquerades as a grocer in order to uncover a drugs ring.· a senior member of the secret service
: underground organization/newspaper/movement etc one that is secret and opposes the government, especially when it is too dangerous to do this publicly: · Slowly, the underground resistance movement grew.· Nearly 2,000 defeated fighters joined the underground Communist forces concealed in the Mekong delta.· He was suspended from his job for writing an editorial in an underground paper.go underground/be forced underground (=become an underground organization): · In 1795, the United Irish Society went underground as a revolutionary movement.
: clandestine organization/force/operation etc one that is secret, and usually illegal: · The doctor was arrested after she was named as a member of a clandestine socialist movement.· His clandestine meetings with PLO officials had been secretly recorded.
: undercover agent/police officer/investigator etc one who works secretly for the police or government in order to catch criminals: · He was arrested after trying to sell guns to an undercover FBI agent.· People dived aside as undercover cops ambushed a planned post office raid.
WORD SETSalarmed, adjectiveallegation, nounamnesty, nounbail, nounbreath test, nouncharge sheet, nouncircumstantial, adjectivecompensation, nouncompensatory, adjectivecomplicity, nouncondemned, adjectivecondemned cell, nounconfess, verbconfession, nounconman, nouncontraband, nouncuff, verbdebug, verbdetain, verbdick, nounenforce, verbfed, nounFederal Bureau of Investigation, nounflogging, nounforensic, adjectivegallows, noungaolbird, noungas chamber, noungibbet, nounguillotine, nounhang, verbhanging, nounhard labour, nounimpeach, verbKC, nounlaunder, verblawsuit, nounleg irons, nounlicensed, adjectivelicensing laws, nounlife, nounlife sentence, nounline-up, nounlynch, verblynch mob, nounpenalty point, nounpenology, nounpolygraph, nounposse, nounprisoner, nounracket, nounracketeer, nounracketeering, nounrake-off, nounransom, nounransom, verbreport, verbreprieve, nounriot, nounshop, verbsilk, nounspeed trap, nounstalker, nounstrip search, nountransport, verbtransportation, nountribunal, nounundercover, adjectivevictim, nounwrongdoing, noun
COLLOCATIONS FROM THE ENTRY an undercover investigation undercover detectives a cop who goes undercover to catch drug dealers He worked undercover in Germany and Northern Ireland.COLLOCATIONS FROM OTHER ENTRIES an undercover (=secret)agentCOLLOCATIONS FROM THE CORPUSNOUN
an undercover investigation undercover detectives a cop who goes undercover to catch drug dealers He worked undercover in Germany and Northern Ireland. an undercover (=secret)agent· The Fedpol had undercover agents there, naturally, but no official presence.· Michael Osborne told investigators that drugs were so prevalent at Cyberzone that undercover agents needed help from fellow deputies working off-duty.· In the guise of travelling labourers they were sent to Wokingham Fair as undercover agents.· I want to apply to become an undercover agent.· Normally, however, he was resident in London, operating as an undercover agent there.· The informant showed gun crates marked with the names of Norinco and Poly Technologies to an undercover agent.· They had undercover agents everywhere in the hotel.
· But it's great fun watching these little monsters give undercover cop Arnie the run-around.· People dived aside as undercover cops ambushed a post office raid.
· The two-year undercover investigation which culminated Thursday, involved 130 searches in 36 states.
· In fact, it was a police exercise and was solely staffed by two undercover officers calling themselves Gary and Aggi.· Aron stated she was willing to pay for services, and she and the undercover officer discussed money.· Annalisa Sellen was one of the undercover officers responsible for the operation.
· There was also widespread disquiet over the nature of the undercover operation which had trapped him.· Postal inspectors changed the name of the business to Island Male, and ran it as an undercover operation.· Dolezal decides to play detective in a one man undercover operation, wandering naively into deathtrap after deathtrap.· They died almost five years ago in the undercover operation near Omagh, Co Tyrone.· According to law-enforcement sources, it was part of Operation Corea, an undercover operation designed to track the flow of heroin.· Police would be allowed to use undercover operations and to tap telephones in the course of anti-Mafia investigations.
· An on-site undercover operative can offer an employer protection without the presence of an armed guard.· Some companies routinely bring in undercover operatives every six to 12 months, Kimmons said.
· But the covert groupings have had their undercover work rumbled by loyalists.· You have people who do undercover work, I believe, like mingle with students or go to political meetings.
WORD FAMILYnouncovercoveragecoveringadjectiveundercovercovered ≠ uncoveredverbcover ≠ uncoveradverbundercover
undercover work is done secretly by the police in order to catch criminals or find out information: an undercover investigationundercover policeman/cop/agent etc undercover detectives► see thesaurus at secret—undercover adverb: a cop who goes undercover to catch drug dealers He worked undercover in Germany and Northern Ireland.