| 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: so called in allusion to a statement in 1936 that the insurgents had four columns marching on Madrid and a fifth column of sympathizers in the city ready to rise and betray it. |
| fifth column n. 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. |
People willing to cooperate with an aggressor against their own country. The term originated in a remark by Francisco Franco, the Spanish dictator, that he was marching on Madrid with four columns of troops, and that there was a “fifth column” of sympathizers within the city ready to help.