n.[theS]

1. 毁灭；垮台
   This hard attitude may have led to his undoing.

   可能就是这种强硬的态度导致了他的垮台。

2. 毁灭（或失败）的原因
   Stress can be the undoing of so many fine players.

   紧张可能是这许多优秀选手失败的原因。

3. 取消；消除
4. 解开；松开；打开

n.

▸the cause of a person's ruin or downfall:

complacency was to be their undoing.