Definition of infiltrate in English:



  • 1Enter or gain access to (an organization, place, etc.) surreptitiously and gradually, especially in order to acquire secret information:

    ‘the organization has been infiltrated by informers’
    • ‘For the next four decades, a small minority from certain Iraqi towns would gradually infiltrate the highest governmental positions as well as the top officer ranks in the army.’
    • ‘It is infiltrating their organizations beyond bombing their training bases.’
    • ‘Mr Santos told reporters that there were indications the security forces had been infiltrated at a very high level.’
    • ‘The initial Federal raid relied upon surprise for safety, and grabbed the evidence after successfully infiltrating the place.’
    • ‘I think they'd recognize if Senator Hatch or I tried to infiltrate the organization.’
    • ‘The organisation has been heavily infiltrated by informers and many of its members are now in jail.’
    • ‘They often disguise their affiliation by wearing civilian clothes, and they often carry arms covertly to infiltrate various places.’
    • ‘It propagates paranoia about the Third World's dark intentions to gatecrash and infiltrate the Western World over a period of time, and take it over eventually.’
    • ‘This is why I sometimes think we should infiltrate the Countryside Alliance - we'd get more cameras pointed at us then…’
    • ‘He said intelligence agents and police informers had infiltrated villages in the area and worked as drivers, masons and hawkers for months to gather information about Veerappan and his men who were suspected to be hiding nearby.’
    • ‘From 1999 until early 2001, Lauder infiltrated the organised racist movement in Canada.’
    • ‘Now that we have a common picture of the communications architecture, we must discuss using information to successfully infiltrate an enemy's position.’
    • ‘Your intrepid blogger promises to infiltrate this suspicious-sounding organization and report the truth!’
    • ‘Well, I believe the electronic surveillance has importance, but we really need to infiltrate the terrorist organizations.’
    • ‘They have infiltrated organizations large and small.’
    • ‘One officer so deeply infiltrated the Communist Party that he traveled to the Soviet Union.’
    • ‘A secret land, infiltrated by humans, and the loss of spirituality is at stake.’
    • ‘They were criminals recruited by an MI6 officer to infiltrate the IRA.’
    • ‘It will take years for the intelligence organizations to infiltrate terrorist organizations and be in a position to carry out these assassinations.’
    • ‘I hope that we continue to have brave men and women who infiltrate these organizations in order to help to protect society.’
    penetrate, invade, intrude on, insinuate oneself into, worm one's way into, sneak into, slip into, creep into, impinge on, trespass on, butt into
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    1. 1.1 Introduce (someone) into an organization, place, etc. surreptitiously, in order for them to acquire secret information:
      ‘they infiltrated an agent into the factory’
      • ‘He was infiltrated back into South Africa as one of the commanders of Operation Vula, with a mission to build viable underground and military structures.’
      • ‘In the near term, we will have few professional agents or informants infiltrated into their network.’
      • ‘We are preparing for ‘zero hour'. We were infiltrated during the battle for Najaf.’
      • ‘I wonder myself if the ‘rebellion’ isn't being in part led by Special Forces agents infiltrated into the city.’
      • ‘Phil continues to work on Nigel, trying to infiltrate him into a terrorist gang he believes is centered at a local mosque.’
      • ‘The army agents, who were infiltrated inside the IRA and Sinn Fein, are releasing the video in the Irish Republic as part of a whistle-blowing campaign aimed at exposing the truth behind the dirty war in Northern Ireland.’
      • ‘And one which involved people who were both infiltrated and who worked from outside.’
      • ‘Make sure you have good radio contact with the forward observer and somehow get him into a putting him on a nearby hill, or it can mean infiltrating him in prior to the attack.’
      • ‘A former British soldier, he had specifically been infiltrated into the ranks of the IRA.’
      • ‘Mugabe has infiltrated his agents into this country and M15 is taking their promises to ‘take out’ key opposition leaders very seriously.’
      • ‘The infiltrated agents heard again and again about the failure of leadership exhibited by commanding officers on the front lines.’
    2. 1.2Medicine (of a tumour, cells, etc.) spread into or invade (a tissue or organ):
      ‘one of the tumours infiltrated the submucosa’
      • ‘Tumor cells also infiltrated the smooth muscle of the ciliary body.’
      • ‘The surrounding stroma was infiltrated by plasma cells and scattered aggregates of lymphocytes, forming follicles with germinal centres.’
      • ‘In this specimen, large lymphoid cells diffusely infiltrated muscle and fibrous tissue.’
      • ‘The tumor infiltrated into the coronary sinus.’
      • ‘The lymphoid cells infiltrating all the organs were small round cells with scanty cytoplasm, morphologically similar to normal lymphocytes.’
  • 2(of a liquid) permeate (something) by filtration:

    ‘virtually no water infiltrates deserts such as the Sahara’
    • ‘Pits occur when water infiltrates a stone's pores and then freezes.’
    • ‘In coastal regions, sea water can infiltrate the rocks, and a salt-water wedge will then form below sea level under the fresh groundwater.’
    • ‘In a few locations, spills of these liquids infiltrated the soil and created very large areas of contaminated groundwater and soil.’
    • ‘The holding pond should be emptied before it is full, when waste waters will infiltrate the soil.’
    • ‘They know about erosion and filter effects on the landscape, but not what happens after water infiltrates the soil.’
    • ‘That allows atmospheric carbon dioxide to infiltrate the weak paste and deeply carbonate the calcium hydroxide and other cement hydrates present.’
    permeate, penetrate, pervade, filter through, percolate through, spread through, seep into, seep through, soak into, flow into, pass into, get into, enter
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    1. 2.1 Cause (a liquid) to permeate something by filtration:
      ‘lignocaine was infiltrated into the wound’
      • ‘To prepare a dysfunctional bundle for fixation, intercellular spaces of the sample were vacuum infiltrated with water, which rendered the parenchyma reasonably transparent and suitable for dissection.’
      • ‘For freeze fractures the glutaraldehyde-fixed cells were infiltrated with 30% glycerol.’
      • ‘The five trocars are removed and an additional 3 mL of the lidocaine/bupivicaine mixture is infiltrated into the port sites.’
      • ‘Leaves were infiltrated with water according to Beyschlag and Pfanz to verify ICS.’
      • ‘Leaves were then infiltrated with deionized water under vacuum three times for 4 min to ensure complete infiltration.’
  • 3Gradually permeate or become a part of:

    ‘computing has infiltrated most professions now’
    • ‘Does western culture and its values infiltrate traditional Indian values?’
    • ‘The fascist bent that infiltrated Argentina in the 1930s was quite popular among conservative artists and intellectuals.’
    • ‘And it's certainly true that our style has infiltrated into the style of singing and congregational worship in this church.’
    • ‘Foreign culture has constantly infiltrated China in the form of weapons and then at the mental and conceptual level.’
    • ‘Spencer said one of the major steps was to encourage followers to enter the ministry of various churches and to infiltrate North America's schools and teaching colleges.’
    • ‘How much of Atheism has infiltrated into legislative and executive branches at all levels of government?’
    • ‘The ensuing Meiji policy of modernization allowed Western ideas, institutions, and culture to infiltrate Japan.’
    • ‘Capitalism has infiltrated the Scottish Socialists' camp.’
    • ‘It reads like a blog, but you only have to look at a couple of the images to know this is a commercially popular side of US culture and quickly infiltrating ours.’
    • ‘Shamanic thought is gradually infiltrating the greater Pagan community.’
    • ‘The discrimination exists across all of society and, according to this research, has infiltrated into the agencies charged with confronting the problem.’
    • ‘Nothing against those particular bands, but their sound has evidently infiltrated the very atmosphere of our fair cities.’
    • ‘Japanese leisure is also infiltrating U.S. culture.’
    • ‘The way we dress, even the way we speak, is impinged on and infiltrated by these alien cultures.’
    • ‘Postmodernists claim that science, no less than religion and literature and philosophy, is infiltrated with culture.’


  • An infiltrating substance or a number of infiltrating cells:

    ‘a chest radiograph revealed a patchy infiltrate in the left lower lobes’
    • ‘His follow-up radiograph 10 days after the initiation of prednisone showed a substantial decrease of the infiltrate.’
    • ‘Although the chest radiograph may be normal initially, subsequent radiographs will reveal an infiltrate, which may extend rapidly, involving one or more lobes as well as the pleura.’
    • ‘The bone marrow was replaced by an infiltrate of blast cells with medium-sized nuclei, multiple nucleoli, and moderate amounts of cytoplasm.’
    • ‘The triads may show a variable degree of ductal and ductular proliferation, and may even demonstrate edema and a neutrophilic infiltrate.’


Middle English (as infiltration): from in- + filtrate.