infiltration

Etymology

From Middle English infiltracioun, from Medieval Latin infiltrātiōnem, infiltrātiō. Morphologically infiltrate + -ion

noun

1. The act or process of infiltrating, as of water into a porous substance, or of a fluid into the cells of an organ or part of the body.
   1. (hydrology, soil science) process by which water on the ground surface enters the soil.
2. The substance which has entered the pores or cavities of a body.
   calcareous infiltrations filling the cavities 1784, Richard Kirwan, Elements of Mineralogy
3. The act of secretly entering a physical location and/or organization.
   No one should be under any illusions about the objective of the Communist Party leadership: it’s long-term, systematic infiltration of social organisations, media and government. By the time China’s infiltration of Australia is readily apparent, it will be too late. 2019, Peter Hartcher, “Power and Paranoia: Why the Chinese government aggressively pushes beyond its borders”, in The Sydney Morning Herald