If you infiltrate a group or organization, you join it in order to gain information, like an employee of a donut shop that infiltrates the competition to try to learn its "secret recipe" for its delicious dough.

  • Pronunciation: / ɪn'fɪltret/
  • English description: enter a group or organization in order to spy on the members
  • Synonyms: penetrate
  • Chinese Translation:  潜入(qian3 ru4)
  • Spanish Translation: infiltrarse
  • ORIGIN: Infiltrate is a verb that is familiar to international spies and undercover agents, who are all adept at joining a group under false pretenses, fitting in, and working their way up to the highest ranks in order to find out as much information as they can about the group. The word can be used more broadly to describe anything that stealthily becomes a part of something else, such as slang words that infiltrate our everyday speech.


  • We don’t need to set this up as we either take a bunch of refugees who will be infiltrated with terrorists, I guarantee you.
  • Instead, the government should be free to infiltrate mosques to monitor for sermons calling for extremism.

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