Infiltrator

[in-fil-treyt, in-fil-treyt] /ɪnˈfɪl treɪt, ˈɪn fɪlˌtreɪt/

verb (used with object), infiltrated, infiltrating.
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), infiltrated, infiltrating.
5.
to pass into or through a substance, place, etc., by or as by filtering.
6.
Pathology. to penetrate tissue spaces or cells.
noun
7.
something that infiltrates.
8.
Pathology. any substance penetrating tissues or cells and forming a morbid accumulation.
/ˈɪnfɪlˌtreɪt/
verb
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 surreptitiously: they infiltrated the party structure
noun
4.
something that infiltrates
5.
(pathol) any substance that passes into and accumulates within cells, tissues, or organs
6.
(pathol) a local anaesthetic solution injected into the tissues to cause local anaesthesia
v.

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

infiltrate in·fil·trate (ĭn-fĭl’trāt’, ĭn’fĭl-)
v. in·fil·trat·ed, in·fil·trat·ing, in·fil·trates

n.
An abnormal substance that accumulates gradually in cells or body tissues.