1. a process in which individuals (or small groups) penetrate an area (especially the military penetration of enemy positions without detection)(Freq. 5) • Derivationally related forms: infiltrate • Topics: military, armed forces, armed services, military machine, war machine • Hypernyms: penetration, incursion 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 • Syn: percolation • Derivationally related forms: infiltrate, percolate (for: percolation) • Hypernyms: filtration