The process of entering or gaining access gradually and stealthily, often for subversive purposes, or the slow passage of liquid through porous material.
From Latin 'infiltrare,' combining 'in-' (into) and 'filtrare' (to filter). Originally a geological term from the 18th century describing water seepage, it acquired military and espionage meanings in the 20th century.
The word beautifully captures how both water and spies operate - slowly, persistently, and often unnoticed until the damage is done. The geological origin is fitting since both processes involve finding the smallest openings and gradually expanding influence or presence.
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