infiltrator

[ in-fil-trey-ter, in-fil-trey- ]

noun

1. 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.

2. 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.

Word History and Origins

Origin of infiltrator¹

infiltrat(e) ( def ) + -or ²( def )

Example Sentences

In Silverman’s telling, the filmmaker, Joris Ivens, a Dutchman working in the United States, is already an undercover infiltrator for Soviet interests when the Spanish Civil War breaks out in 1936.

From New York Times

When Patriot Front members filed a lawsuit against the infiltrator accusing him of “malicious doxxing,” they relied on federal law and invasion of privacy and computer fraud statutes.

From Seattle Times

“I just had the worst infiltrator the org has ever seen,” Brown wrote.

From Seattle Times

But it has become more pointed since a roadside bombing in Israel in March, which it blamed on an Hezbollah infiltrator.

From Reuters

Amy Cooter, a researcher at Middlebury Institute’s Center on Terrorism, Extremism, and Counterterrorism, has written extensively about the Justice Department’s failed 2012 prosecution of members of the Hutaree militia group accused of plotting a violent revolt against the government, a case that relied heavily on an undercover agent and a paid infiltrator.

From Washington Post

Related Words

• spy