1. A hit or impact that causes immediate death. The warrior swiftly dealt a death blow to his adversary on the battlefield.
2. An event that causes the abrupt end of something. His arrest and subsequent conviction was a death blow to his successful career as an attorney. Despite the company's recent success, the massive recall proved to be its death blow.
a death blow
If something is a death blow to a process, situation, or organization, it causes it to end or fail. This could deal a death blow to the collapsing national economy. They warned that the deportations would be a death blow to the peace process.