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
At least 13 people were killed and 24 were injured after Israeli forces infiltrated the Beit Jinn village in southern Syria to capture two members of Jama’a Islamiya, a Lebanese Islamist militant group.
—
Mostafa Salem, CNN Money, 28 Nov. 2025
Flying on the wind, sometimes miles ahead of the fire front, a firestorm of glowing embers infiltrates the home through unsealed cracks and vents, taking advantage of the combustible furniture and drapes to burn it down from within.
—New Atlas, 27 Nov. 2025
The documentary includes exclusive witness testimony, expert forensic analysis, and detailed graphic reconstructions that follow the moment the thieves infiltrated the Louvre’s perimeter and disappeared with the priceless jewels.
—Jason Pham, StyleCaster, 26 Nov. 2025
During one of those encounters, the Mind Flayer pumps some sort of dust into his body, which in turn allows the shadowy creature to increasingly infiltrate Will.
—Dessi Gomez, Deadline, 26 Nov. 2025
See All Example Sentences for infiltrate
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Mostafa Salem, CNN Money, 28 Nov. 2025
Flying on the wind, sometimes miles ahead of the fire front, a firestorm of glowing embers infiltrates the home through unsealed cracks and vents, taking advantage of the combustible furniture and drapes to burn it down from within.
—New Atlas, 27 Nov. 2025
The documentary includes exclusive witness testimony, expert forensic analysis, and detailed graphic reconstructions that follow the moment the thieves infiltrated the Louvre’s perimeter and disappeared with the priceless jewels.
—Jason Pham, StyleCaster, 26 Nov. 2025
During one of those encounters, the Mind Flayer pumps some sort of dust into his body, which in turn allows the shadowy creature to increasingly infiltrate Will.
—Dessi Gomez, Deadline, 26 Nov. 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 29 Nov. 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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