LEARNit Dictionary
fifth columnist
noun
/ˌfɪfθ ˈkɒləmnɪst/
UK
/ˌfɪfθ ˈkɑːləmnɪst/
US
1
a person who is working secretly to help the enemy of the country or organization they are in
ستون پنجم, نفوذی, عامل نفوذی