infiltration

noun

1. the act or process of infiltrating.
2. the state of being infiltrated.
3. something that infiltrates; an infiltrate.
4. Military.
   1. a method of attack in which small bodies of soldiers or individual soldiers penetrate the enemy’s line at weak or unguarded points in order to assemble behind the enemy position and attack it from the rear, harass enemy rear-area installations, etc.
   2. a system of transporting troops or vehicles at extended and irregular intervals so as to avoid enemy observation or attack, especially from the air.
5. Geology. the seepage of water into soil or rock.Compare percolation(def 3).

n.

1. The act or process of infiltrating.
2. The state of being infiltrated.
3. The gas, fluid, or dissolved matter that has entered a substance, cell, or tissue.