the final nail in the coffin
1
the last event, action, or circumstance that causes something to fail or end
The idiom "the final nail in the coffin" has its origins in the act of nailing shut a coffin after a person has died. It refers to the last event or action that seals the outcome and makes it irreversible. The phrase can also be used to describe the point of no return, where there is no possibility of recovery or redemption.
- Rising interest rates were the final nail in the coffin for many overextended homeowners, pushing them into default and foreclosure.
- The data breach was the final nail in the coffin for the company's already damaged reputation - customers lost all trust after that.
- When the star witness changed her story, it was the final nail in the coffin for the defendant's case.