- deader than a doornail
- *dead as a dodo & *dead as a doornail & deader than a doornaildead; no longer in existence. (*Also: as \deader than a doornail.) •
That silly old idea is dead as a dodo.
•When I tried to start my car this morning, I discovered that the battery was deader than a doornail.
Dictionary of American idioms. 2013.