infiltrate

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

verb (used with object)

infiltrated, infiltrating 

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)

infiltrated, infiltrating 

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

Other Word Forms

• infiltrative adjective
• infiltrator noun
• reinfiltrate verb
• uninfiltrated adjective
• infiltration noun

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

They infiltrate the rivers where they grow until they return to sea to reproduce.

Read more on Barron's

Fighting in the east centres around control of the key logistical hub Pokrovsk, which hundreds of Russian soldiers have infiltrated in recent weeks, weakening Ukrainian defences.

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The WHO warned Wednesday that the tobacco industry was trying to infiltrate and undermine the conference.

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We’ve been too slow for too long to confront hate merchants seeking to infiltrate the right.

Read more on The Wall Street Journal

In an urban environment, Russian soldiers sometimes infiltrate by dressing up as locals or as Ukrainian military, says Mashovets.

Read more on BBC

Related Words

• penetrate 
• permeate 
• pervade