infiltrate

[ in-fil-treyt, in-fil-treyt ]

verb (used with object)

, in·fil·trat·ed, in·fil·trat·ing.

1. to filter into or through; permeate.
2. to cause to pass in by filtering.
3. to move into (an organization, country, territory, or the like) surreptitiously and gradually, especially with hostile intent:

   The troops infiltrated the enemy lines.

4. to pass a small number of (soldiers, spies, or the like) into a territory or organization clandestinely and with hostile or subversive intent:

   The intelligence agency infiltrated three spies into the neighboring country.

verb (used without object)

, in·fil·trat·ed, in·fil·trat·ing.

1. to pass into or through a substance, place, etc., by or as by filtering.
2. Pathology. to penetrate tissue spaces or cells.

noun

1. something that infiltrates.
2. Pathology. any substance penetrating tissues or cells and forming a morbid accumulation.

infiltrate

/ ˈɪnfɪlˌtreɪt /

verb

1. to undergo or cause to undergo the process in which a fluid passes into the pores or interstices of a solid; permeate
2. military to pass undetected through (an enemy-held line or position)
3. to gain or cause to gain entrance or access surreptitiously

   they infiltrated the party structure

noun

1. something that infiltrates
2. pathol any substance that passes into and accumulates within cells, tissues, or organs
3. pathol a local anaesthetic solution injected into the tissues to cause local anaesthesia

Derived Forms

• ˈinfilˌtrative, adjective
• ˌinfilˈtration, noun
• ˈinfilˌtrator, noun

Other Words From

• in·fil·tra·tive [in, -fil-trey-tiv, in-, fil, -tr, uh, -], adjective
• in·fil·tra·tor [in, -fil-trey-ter, in-, fil, -trey-], noun
• re·in·fil·trate verb reinfiltrated reinfiltrating
• un·in·fil·trat·ed adjective

Word History and Origins

Origin of infiltrate¹

First recorded in 1750–60; in- ² + filtrate

Word History and Origins

Origin of infiltrate¹

C18: from in- ² + filtrate

Example Sentences

“We have to have a larger portion of our groundwater recharge coming from managing rainwater, in getting rid of impervious surfaces and letting it infiltrate,” Winter said.

From Los Angeles Times

“They will infiltrate a legitimate business, take control of its distribution networks and use it to move other illegal items, including stolen food.”

From BBC

Though he managed GOP political campaigns from Pat Buchanan in 1992 to Mitt Romney in 2012, Erickson is best known for his romantic relationship with Russian agent Maria Butina, who used Erickson’s connections to try to infiltrate the National Rifle Association.

From Slate

She believes there has been a coordinated effort by well-connected progressive groups like the Sierra Club to infiltrate and divide small, conservative communities all over the country, to take over school boards and city councils, and to turn residents against Trump.

From Los Angeles Times

With the psychological deftness of a cult leader, Trump is able to infiltrate the shadowed corners of America’s consciousness, casting a sinister silhouette that bends reality into a fevered hallucination of chaos and bloodlust.

From Salon

Related Words

• penetrate
• permeate
• pervade