as dead as a doornail

The phrase "as dead as a doornail" is an idiom used to describe something or someone that is completely without life, non-functioning, or irrevocably broken. It implies that the object or person being referred to is no longer capable of being revived or revived. The phrase is thought to have originated from the practice of securing or reinforcing doors with large iron nails called doornails, which were hammered in and clench up, making them difficult to remove without damaging them. Once a doornail was hammered in, it could not be easily dislodged, making it "dead" in the sense that it was permanently fixed and rendered inanimate.