infiltrator
Americannoun
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a soldier, intelligence agent, or other person who moves surreptitiously and gradually into an organization, territory, community, or the like, especially with hostile intent.
Using a false name, the infiltrator participated in meetings and prep sessions with the protest group and had complete access to their documentation.
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a person or thing that causes one substance to pass into another by filtering.
The roots of wetland plants serve as massive water infiltrators, allowing more rainwater to seep into the soil and recharge underground aquifers.
Etymology
Origin of infiltrator
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
They had to go with the “selfie cruise” narrative, which meant they had to treat them with basic decency because they couldn’t pass them off as some evil infiltrator.
From Slate • Sep. 29, 2025
“I just had the worst infiltrator the org has ever seen,” Brown wrote.
From Seattle Times • Aug. 8, 2023
Trevante Rhodes, who was super in “Moonlight,” plays the infiltrator, a man torn between his job and his race.
From Washington Times • Feb. 23, 2021
Moreover, much of Mitchell’s narrative rotates among a broad array of characters: the tunnelers, the would-be escapees, a Stasi infiltrator and his bosses, journalists and media executives, and top officials in the U.S. government.
From Washington Post • Dec. 9, 2016
He considered that perhaps they were just checking him out, making sure he wasn’t an FBI infiltrator, but as the weeks went by, C.P. ached with disappointment.
From "The Best of Enemies" by Osha Gray Davidson
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
