Infiltration
WordNet
noun
(1) A process in which individuals (or small groups) penetrate an area (especially the military penetration of enemy positions without detection)
(2) The slow passage of a liquid through a filtering medium
"The percolation of rainwater through the soil"
"The infiltration of seawater through the lava"
WiktionaryText
Noun
- 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.
- The substance which has entered the pores or cavities of a body.
- The act of entering a physical location and/or organization secretly.