the action of entering or gaining access to an organization or place surreptitiously, especially in order to acquire secret information or cause damage

the army fenced parts of the border in an effort to stop militant infiltration

cross-border infiltrations

permeation of a liquid into something by filtration

improved water infiltration into the soil

this mosaic was in danger of being lost because of the infiltration of rainwater

the process of gradually permeating or becoming a part of something

the gradual infiltration of Boyce's music into the national consciousness