Definition
- literary
A very serious and dangerous enemy, threat, or situation.
死敌，致命危险，严重威胁
After years of competition, they have become mortal enemies.
经过多年的竞争，他们已经成为不共戴天的敌人。
He was viewed as a mortal threat to the company's existence.
他被视为对公司存亡的致命威胁。
They found themselves in mortal danger when the plane's engines stopped working.
当飞机的引擎停止运转时，他们发现自己处于生死攸关的危险中。