infiltrator

Từ điển WordNet v3.1 - WordNet Dictionary

noun

1. someone who takes up a position surreptitiously for the purpose of espionage
• Derivationally related forms:
infiltrate
• Hypernyms:
spy, undercover agent
2. an intruder (as troops) with hostile intent
• Derivationally related forms:
infiltrate
• Hypernyms:
intruder, interloper, trespasser