verb (used with object), in·fil·trat·ed, in·fil·trat·ing.

  1. to filter into or through; permeate.
  2. to cause to pass in by filtering.
  3. to move into (an organization, country, territory, or the like) surreptitiously and gradually, especially with hostile intent: The troops infiltrated the enemy lines.
  4. to pass a small number of (soldiers, spies, or the like) into a territory or organization clandestinely and with hostile or subversive intent: The intelligence agency infiltrated three spies into the neighboring country.

verb (used without object), in·fil·trat·ed, in·fil·trat·ing.

  1. to pass into or through a substance, place, etc., by or as by filtering.
  2. Pathology. to penetrate tissue spaces or cells.


  1. something that infiltrates.
  2. Pathology. any substance penetrating tissues or cells and forming a morbid accumulation.


  1. to undergo or cause to undergo the process in which a fluid passes into the pores or interstices of a solid; permeate
  2. military to pass undetected through (an enemy-held line or position)
  3. to gain or cause to gain entrance or access surreptitiouslythey infiltrated the party structure


  1. something that infiltrates
  2. pathol any substance that passes into and accumulates within cells, tissues, or organs
  3. pathol a local anaesthetic solution injected into the tissues to cause local anaesthesia

1758, of fluids, from in- (2) “in” + filtrate. Related: Infiltrated; infiltrating. Military sense of “penetrate enemy lines” attested from 1934.


  1. To cause a liquid to permeate a substance by passing through its interstices or pores.
  2. To permeate a porous substance with a liquid or gas.


  1. An abnormal substance that accumulates gradually in cells or body tissues.
52 queries 0.664