[in.fil.trate] vb -trat.ed ; -trat.ing vt (1758) 1: to cause (as a liquid) to permeate something by penetrating its pores or interstices
2: to pass into or through (a substance) by filtering or permeating
3: to pass (troops) singly or in small groups through gaps in the enemy line
4: to enter or become established in gradually or unobtrusively usu. for subversive purposes "the intelligence staff had been infiltrated by spies" ~ vi: to enter, permeate, or pass through a substance or area by filtering or by insinuating gradually -- infiltrate n -- in.fil.tra.tion n -- in.fil.tra.tive adj -- in.fil.tra.tor n