n.背叛；脱党；离会

His defection to the other side was the ultimate betrayal. 他变节投向另一方是最终的背叛。

In the game, cooperation and defection result in differing payoffs depending on what the other participants do. 在游戏中，合作和背叛所得到的后果将根据其他参与者的作为而定。

The defection of a large number of back-benchers brought down the last government. 大量的不居要职的普通议员脱党，造成前任政府的垮台。