infiltrator

Noun infiltrator has 2 senses

• infiltrator(n = noun.person) - someone who takes up a position surreptitiously for the purpose of espionage;
is a kind of spy, undercover agent
Derived form verb infiltrate₂

• infiltrator(n = noun.person) - an intruder (as troops) with hostile intent;
is a kind of interloper, intruder, trespasser
Derived form verb infiltrate₄