1.A member of a clandestine group of people who work subversively within a group,organization,or country in order to betray it to an allied outside force.
一个秘密团体的成员，在某个群体、组织或国家内部进行颠覆活动，以便将其出卖给外部的盟友势力。
In the US during the Cold War,there was constant fear and suspicion of people supposedly working as fifth columnists to spread the influence of communism from within.
英语成语:fifth columnist
In the US during the Cold War,there was constant fear and suspicion of people supposedly working as fifth columnists to spread the influence of communism from within.
