infiltration
noun
[ ɪnfɪlˈtreɪʃ(ə)n ]
• 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"
• permeation of a liquid into something by filtration.
• "improved water infiltration into the soil"
• the process of gradually permeating or becoming a part of something.
• "the gradual infiltration of Boyce's music into the national consciousness"
