1. drive a nail into sb's coffin : 促某人早死；
及物动词
1. 棺材;灵柩
A coffin is a box in which a dead body is buried or cremated.
2. 促使…失败（或完结）的因素
If you say that one thing is a nail in the coffin of another thing, you mean that it will help bring about its end or failure.
1. box in which a corpse is buried or cremated
Synonym: casket