Pronunciation: /fɪfθ ˈkɒləmnɪst/
noun a person who works secretly to aid an enemy; traitor
A1 A fifth columnist is someone who secretly works against their own country.
A2 During wartime, fifth columnists can pose a serious threat to national security.
B1 The government suspected that there were fifth columnists within the country leaking information to the enemy.
B2 The spy agency was tasked with uncovering and neutralizing any fifth columnists operating in the region.
C1 The fifth columnist's actions were eventually exposed, leading to their arrest and prosecution.
C2 The fifth columnist's betrayal shocked the nation and caused widespread outrage.
adjective relating to or characteristic of a fifth columnist
A1 I heard that the new student is a fifth columnist, always causing trouble in class.
A2 The company suspected that there was a fifth columnist leaking sensitive information to competitors.
B1 The political party was divided by accusations of having fifth columnist members working against their own interests.
B2 The spy agency uncovered a network of fifth columnist operatives embedded in various government agencies.
C1 The military was on high alert for any signs of fifth columnist activity within their ranks.
C2 The diplomat was accused of being a fifth columnist for a foreign government, leading to his expulsion from the country.
formal The government suspected that the spy was working as a fifth columnist within the country.
informal I heard that there's a fifth columnist in our group leaking information to our competitors.
slang Watch out for that guy, he's a total fifth columnist.
figurative Her constant criticism of the company makes her seem like a fifth columnist in our team.
fifth columnized
fifth columnists
more fifth columnist
most fifth columnist
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will be fifth columnists
have been fifth columnists
are being fifth columnists
fifth columnist
fifth column
to fifth column
fifth columning
fifth columned