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
Vecna uses this friendly guise to manipulate and lure the Hawkins kids, presenting himself as a protector while infiltrating their minds and drawing them into danger.
—
Allison Degrushe, Entertainment Weekly, 5 Dec. 2025
In a statement on Telegram, the General Staff said a Russian sabotage and reconnaissance unit briefly infiltrated the outskirts of the settlement, exploiting weather conditions.
—Amanda Castro, MSNBC Newsweek, 4 Dec. 2025
Although scammers and frauds have infiltrated the world of social enterprise, legit companies can be uplifting for all involved.
—Greg Mellen, Oc Register, 28 Nov. 2025
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
See All Example Sentences for infiltrate
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Allison Degrushe, Entertainment Weekly, 5 Dec. 2025
In a statement on Telegram, the General Staff said a Russian sabotage and reconnaissance unit briefly infiltrated the outskirts of the settlement, exploiting weather conditions.
—Amanda Castro, MSNBC Newsweek, 4 Dec. 2025
Although scammers and frauds have infiltrated the world of social enterprise, legit companies can be uplifting for all involved.
—Greg Mellen, Oc Register, 28 Nov. 2025
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
See All Example Sentences for infiltrate
Cite this Entry
“Infiltrate.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/infiltrate. Accessed 6 Dec. 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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