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.
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.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
How to use infiltrator in a sentence
Nor it just the Post—"infiltrator" is also used by the Israeli news site Ynet and by the Religious Zionist Arutz Sheva.
One, that he might possibly have been an infiltrator working for the FBI?Warren Commission (10 of 26): Hearings Vol. X (of 15) | The President's Commission on the Assassination of President Kennedy