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
But with the March 17 primary just days away, fresh faces are vying to replace experienced lawmakers and outside campaign cash has infiltrated a string of races for the Illinois House and Senate.
—
Chicago Tribune, 16 Mar. 2026
Still, Frankel told EW in the oral history piece that production designer Jess Gonchor secretly infiltrated the Vogue offices to scope Wintour's workspace — and replicated its aesthetic for the movie.
—Joey Nolfi, Entertainment Weekly, 16 Mar. 2026
For instance, sprinkling cinnamon around entry points while also using a vinegar spray can help create a double barrier against ants attempting to infiltrate your home.
—Alexandra Kelly, Martha Stewart, 13 Mar. 2026
In 2014, quagga mussels infiltrated the water pumps of Cave Creek, racking up a bill of nearly $50,000 for emergency repairs.
—Shi En Kim, AZCentral.com, 13 Mar. 2026
See All Example Sentences for infiltrate
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Chicago Tribune, 16 Mar. 2026
Still, Frankel told EW in the oral history piece that production designer Jess Gonchor secretly infiltrated the Vogue offices to scope Wintour's workspace — and replicated its aesthetic for the movie.
—Joey Nolfi, Entertainment Weekly, 16 Mar. 2026
For instance, sprinkling cinnamon around entry points while also using a vinegar spray can help create a double barrier against ants attempting to infiltrate your home.
—Alexandra Kelly, Martha Stewart, 13 Mar. 2026
In 2014, quagga mussels infiltrated the water pumps of Cave Creek, racking up a bill of nearly $50,000 for emergency repairs.
—Shi En Kim, AZCentral.com, 13 Mar. 2026
See All Example Sentences for infiltrate
Cite this Entry
“Infiltrate.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/infiltrate. Accessed 18 Mar. 2026.
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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