infiltrate
verb
in·fil·trate
ˈin-(ˌ)fil-ˌtrāt 
in-ˈfil-
in-ˈfil-
infiltrated; infiltrating
1
: to enter or become established in gradually or unobtrusively usually for subversive purposes
the intelligence staff had been infiltrated by spies
2
: to pass (troops) singly or in small groups through gaps in the enemy line
3
: to pass into or through (a substance) by filtering or permeating
4
: to cause (something, such as a liquid) to permeate something by penetrating its pores or interstices
: to enter, permeate, or pass through a substance or area by filtering or by insinuating gradually
infiltrate
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.
Recent Examples on the Web
Words change meaning over time, slang infiltrates the mainstream, and sometimes, a little creative license is acceptable.
—
Jerry Weissman, Forbes.com, 26 June 2025
Such attacks have already infiltrated U.S. water and wastewater systems, according to the non-profit think tank Center for Internet Security, which briefed law enforcement on Friday.
—Pierre Thomas, ABC News, 21 June 2025
There is this massive explosion that happens when you guys infiltrate Grady's farmhouse.
—EW.com, 20 June 2025
On Law & Order: Organized Crime, Stabler joined the New York Police Department's Organized Crime Control Bureau to infiltrate the world of seedy crime syndicates, including some that wish to seek revenge on him and his family.
—Christopher Rudolph, People.com, 13 June 2025
See All Example Sentences for infiltrate
Examples are automatically compiled from online sources to
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Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
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Jerry Weissman, Forbes.com, 26 June 2025
Such attacks have already infiltrated U.S. water and wastewater systems, according to the non-profit think tank Center for Internet Security, which briefed law enforcement on Friday.
—Pierre Thomas, ABC News, 21 June 2025
There is this massive explosion that happens when you guys infiltrate Grady's farmhouse.
—EW.com, 20 June 2025
On Law & Order: Organized Crime, Stabler joined the New York Police Department's Organized Crime Control Bureau to infiltrate the world of seedy crime syndicates, including some that wish to seek revenge on him and his family.
—Christopher Rudolph, People.com, 13 June 2025
See All Example Sentences for infiltrate
Cite this Entry
“Infiltrate.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/infiltrate. Accessed 3 Jul. 2025.
Copy CitationKids Definition
infiltrate
verb
in·fil·trate
in-ˈfil-ˌtrāt
ˈin-(ˌ)fil-
ˈin-(ˌ)fil-
infiltrated; infiltrating
1
: to pass into or through by filtering
2
: to enter or become established gradually or secretly
Medical Definition
infiltrate
1 of 2 verb
in·fil·trate
in-ˈfil-ˌtrāt
ˈin-(ˌ)
ˈin-(ˌ)
infiltrated; infiltrating
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
: to enter, permeate, or pass through a substance or area
infiltrate
2 of 2 noun
: 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
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