fifth column

 Longman Dictionary of Contemporary English 5++朗文当代英语 5++LDOCE 5++朗文 5++ˌfifth ˈcolumn noun [countable]  SPYa group of people who work secretly to help the enemies of the country where they live or the organization in which they work 第五纵队〔指从事秘密活动、协助敌军或对手的一群人〕 —fifth columnist noun [countable]

ˌfifth ˈcolumn nounChineseSyllable  

fifth column
ˌfifth ˈcolumn noun [countable]
a group of people who work secretly to help the enemies of the country where they live or the organization in which they work
—fifth columnist noun [countable]

fifth columnBrE /ˌfɪfθ ˈkɒləm/ 🔊NAmE /ˌfɪfθ ˈkɑːləm/ 🔊 nouna group of people working secretly to help the enemy of the country or organization they are in 第五纵队（为所在国家或组织的敌人秘密工作的一群人）▸ fifth columnist BrE /ˌfɪfθ ˈkɒləmnɪst/ 🔊NAmE /ˌfɪfθ ˈkɑːləmnɪst/ 🔊 noun