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
Another aspect is that Netanyahu might have traitors in his government, like legitimate traitors that infiltrated.
—
Jordan King, MSNBC Newsweek, 19 Sep. 2025
Over time, these substances may infiltrate groundwater, creating serious long-term health concerns, degrading habitats, and endangering communities that rely on those resources.
—Michaela Rychetska, JSTOR Daily, 18 Sep. 2025
Martin Suarez is the only deep-undercover FBI agent in history to have infiltrated a Colombian drug cartel.
—Martin Suarez, Rolling Stone, 13 Sep. 2025
Poland this week shot down Russian drones that infiltrated its airspace, prompting NATO to invoke Article 4.
—Jonathan Easley, The Hill, 11 Sep. 2025
See All Example Sentences for infiltrate
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Jordan King, MSNBC Newsweek, 19 Sep. 2025
Over time, these substances may infiltrate groundwater, creating serious long-term health concerns, degrading habitats, and endangering communities that rely on those resources.
—Michaela Rychetska, JSTOR Daily, 18 Sep. 2025
Martin Suarez is the only deep-undercover FBI agent in history to have infiltrated a Colombian drug cartel.
—Martin Suarez, Rolling Stone, 13 Sep. 2025
Poland this week shot down Russian drones that infiltrated its airspace, prompting NATO to invoke Article 4.
—Jonathan Easley, The Hill, 11 Sep. 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 21 Sep. 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
Love words? Need even more definitions?
Merriam-Webster unabridged
Share