/ Thesaurus / I Synonyms of infiltrator Find synonyms for: Noun1. infiltrator, spy, undercover agentusage: someone who takes up a position surreptitiously for the purpose of espionage2. infiltrator, intruder, interloper, trespasserusage: an intruder (as troops) with hostile intentWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: devout Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language