infiltrator

noun

Etymology: Etymology tree English infiltrate Old French -eorbor. Middle English -our Proto-Indo-European *-tōr Proto-Italic *-tōr Latin -torlbor. English -or English infiltrator From infiltrate + -or.

1. One who infiltrates an organization or territory; an undercover or covert agent.

   “Sometimes Israelis were attacked by Arab infiltrators, and hardly a month went by without a West Jerusalemite either being killed or wounded.”

   “Suddenly, one of the cadre appeared from out of the darkness. "Hello, soldier", he said. "Do you have a light?” “Sure,” Jack replied, digging into his pocket for a book of matches. “Soldier! You are dead!” exclaimed the cadre. Jack had failed to challenge the infiltrator. The password was “Bronx”, the counter password was “Bombers”.”