in·​fil·​trate | \ in-ˈfil-ˌtrāt How to pronounce infiltrate (audio) , ˈin-(ˌ)fil- How to pronounce infiltrate (audio) \
infiltrated; infiltrating

Definition of infiltrate

transitive verb

1 : to cause (something, such as a liquid) to permeate something by penetrating its pores or interstices
2 : to pass into or through (a substance) by filtering or permeating
3 : to pass (troops) singly or in small groups through gaps in the enemy line
4 : to enter or become established in gradually or unobtrusively usually for subversive purposes the intelligence staff had been infiltrated by spies

intransitive verb

: to enter, permeate, or pass through a substance or area by filtering or by insinuating gradually

Keep scrolling for more

Other Words from infiltrate

infiltrate noun
infiltration \ ˌin-​(ˌ)fil-​ˈtrā-​shən How to pronounce infiltration (audio) \ noun
infiltrative \ ˈin-​(ˌ)fil-​ˌtrā-​tiv How to pronounce infiltrative (audio) , in-​ˈfil-​trə-​ \ adjective
infiltrator \ in-​ˈfil-​ˌtrā-​tər How to pronounce infiltrator (audio) , ˈin-​(ˌ)fil-​ How to pronounce infiltrator (audio) \ noun

Examples of infiltrate in a Sentence

The gang was infiltrated by undercover agents. Attempts to infiltrate undercover agents into the gang have failed. Water can easily infiltrate the soil.
See More
Recent Examples on the Web Hailed as one of the best movies of the year, Bong Joon-ho’s Parasite is rife with class tensions, chronicling the poor Kim family’s attempt to infiltrate the rich Park family’s household one person at a time. Christian Holub,, "Parasite director Bong Joon-ho explains the art of controlled chaos," 12 Nov. 2019 China’s lawless efforts to infiltrate the American academy and high-tech industries are not an invention of anti-Communist fanatics. Jonathan S. Tobin, National Review, "Don’t Dismiss Communist China’s Critics," 23 July 2019 Luckily, not only did Coinbase and an outside researcher notice the bugs, but Coinbase picked up on the attack before any money could be stolen or the network could be infiltrated. Emily Dreyfuss, WIRED, "Security News This Week: Hackers Used Two Firefox Zero Days to Hit a Crypto Exchange," 22 June 2019 Far-rightists have also organized efforts to infiltrate local and state GOP offices. Erin Corbett, Fortune, "Do Abortion Bans Pave the Way for Forced Sterilization?," 5 June 2019 Mousalimas was barely 18 when he was recruited to be part of a special battalion of Americans of Greek descent, who were infiltrated behind German lines into occupied Greece and Yugoslavia. Carl Nolte, San Francisco Chronicle, "Secret World War II work behind enemy lines earns Bay Area man high honor," 21 Mar. 2018 Catra and the Horde have sort of stepped up their game in a lot of ways and are finding new ways to infiltrate and break down the defenses of the Rebellion. Patrick Gomez,, "She-ra showrunner Noelle Stevenson breaks down the epic season 4 trailer," 24 Oct. 2019 An indictment said Woodson and an unnamed co-conspirator would infiltrate the Snapchat accounts of their minor victims, and lock them out of the app by changing their passwords. Mario Ariza,, "Snapchat sextortionist, 29, guilty of preying on minors," 2 Oct. 2019 Baltimore’s government was struck in May by hackers who sought tens of thousands of dollars from the city after infiltrating computer systems and shutting down a majority of city servers. Luke Broadwater,, "Baltimore IT department uses ‘mind-boggling,' outdated data storage method, audit finds," 27 Sep. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'infiltrate.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of infiltrate

1758, in the meaning defined at transitive sense 1

Keep scrolling for more

Learn More about infiltrate

Time Traveler for infiltrate

Time Traveler

The first known use of infiltrate was in 1758

See more words from the same year

Statistics for infiltrate

Last Updated

26 Nov 2019

Cite this Entry

“Infiltrate.” The Dictionary, Merriam-Webster Inc., Accessed 7 December 2019.

Keep scrolling for more

More Definitions for infiltrate


How to pronounce infiltrate (audio) How to pronounce infiltrate (audio)

English Language Learners Definition of infiltrate

: to secretly enter or join (something, such as a group or an organization) in order to get information or do harm
: to cause (someone) to secretly enter or join a group, organization, etc.
technical : to pass into or through (something)


in·​fil·​trate | \ in-ˈfil-ˌtrāt How to pronounce infiltrate (audio) , ˈin-(ˌ) How to pronounce infiltrate (audio) \
infiltrated; infiltrating

Medical Definition of infiltrate

 (Entry 1 of 2)

transitive verb

1 : to cause (as a liquid) to permeate something by penetrating its pores or interstices infiltrate tissue with a local anesthetic
2 : to pass into or through (a substance) by filtering or permeating

intransitive verb

: to enter, permeate, or pass through a substance or area



Medical Definition of infiltrate (Entry 2 of 2)

: something that passes or is caused to pass into or through something by permeating or filtering especially : a substance that passes into the bodily tissues and forms an abnormal accumulation a lung infiltrate

Keep scrolling for more

Comments on infiltrate

What made you want to look up infiltrate? Please tell us where you read or heard it (including the quote, if possible).


the study of flags

Get Word of the Day daily email!

Test Your Vocabulary

Semantic Drift Quiz

  • a twisty river
  • Which of the following was once a synonym for fun?
Spell It

Can you spell these 10 commonly misspelled words?

Bee Cubed

Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!