infiltration

noun4

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.
2. •
   The act of secretly entering a physical location and/or organization.
3. •
   process by which water on the ground surface enters the soil.
4. •
   The substance which has entered the pores or cavities of a body.