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
Tiny beads, big discoveries To trace how nanoplastics infiltrate skin cells, Xu’s team created their own plastic beads and immersed them in seawater collected off the Corpus Christi coast.
—
Neetika Walter, Interesting Engineering, 17 Oct. 2025
Hunter could always shoot, but help defenders would stray off him if a driver infiltrated the lane.
—Fred Katz, New York Times, 16 Oct. 2025
Harmful bacteria and other microorganisms could have infiltrated the city's water system due to the recent water main breaks, according to the City of Globe Water Department and Gila County Public Health and Community Services.
—Helen Rummel, AZCentral.com, 16 Oct. 2025
From Taylor’s return to radio and late-night interviews to brand activations and more, TS12 has completely infiltrated the mainstream in a way that TS11 did not.
—Eric Renner Brown, Billboard, 14 Oct. 2025
See All Example Sentences for infiltrate
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Neetika Walter, Interesting Engineering, 17 Oct. 2025
Hunter could always shoot, but help defenders would stray off him if a driver infiltrated the lane.
—Fred Katz, New York Times, 16 Oct. 2025
Harmful bacteria and other microorganisms could have infiltrated the city's water system due to the recent water main breaks, according to the City of Globe Water Department and Gila County Public Health and Community Services.
—Helen Rummel, AZCentral.com, 16 Oct. 2025
From Taylor’s return to radio and late-night interviews to brand activations and more, TS12 has completely infiltrated the mainstream in a way that TS11 did not.
—Eric Renner Brown, Billboard, 14 Oct. 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 19 Oct. 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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