nemesis

1. N-UNCOUNT The nemesis of a person or thing is a situation, event, or person which causes them to be seriously harmed, especially as a punishment. 严重惩罚[oft with poss]

The new mathematics test will become the nemesis of teachers. 新的数学测试将会是对老师们的严重惩罚。

2. N-COUNT A person's nemesis is their opponent or rival, especially one who has been their opponent or rival for a long time. 天敌

Sun Microsystems gave up its legal fight with Microsoft and agreed to cooperate with its longtime nemesis. 太阳微系统放弃了和微软的官司，与这家自己竞争了多年的主要对手携手合作。