If food, wood, or another substance is rotten, it has decayed and can no longer be used.
The smell outside this building is overwhelming – like rotten eggs.
这栋大楼外面的气味让人无法忍受--就像臭鸡蛋的味道。
If you describe something as rotten, you think it is very unpleasant or of very poor quality.
I personally think it's a rotten idea.
我个人认为这是个馊主意。
If you feel rotten, you feel bad, either because you are ill or because you are sorry about something.
I had rheumatic fever and spent that year feeling rotten.
我得了风湿热,那一年感觉很糟。