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Related to fifth column: fifth estate
A clandestine subversive organization working within a country to further an invading enemy's military and political aims.
[First applied in 1936 to rebel sympathizers inside Madrid when four columns of rebel troops were attacking that city.]
fifth col′um·nism (kŏl′əm-nĭz′əm) n.
fifth columnist n.
1. (Historical Terms) (originally) a group of Falangist sympathizers in Madrid during the Spanish Civil War who were prepared to join the four columns of insurgents marching on the city
2. any group of hostile or subversive infiltrators; an enemy in one's midst
fifth columnist n
1. a group of people who act traitorously and subversively out of a secret sympathy with an enemy of their country.
2. (originally) Franco sympathizers in Madrid during the Spanish Civil War: the insurgents had four columns marching on Madrid and a “fifth column” of supporters already in the city.
fifth′ col′umnist, n.
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|Noun||1.||fifth column - a subversive group that supports the enemy and engages in espionage or sabotage; an enemy in your midst|
social unit, unit - an organization regarded as part of a larger social group; "the coach said the offensive unit did a good job"; "after the battle the soldier had trouble rejoining his unit"