Wiktionary
a. (context simile English) unquestionably dead. Used for both inanimate objects and once living beings.
Wikipedia
Dead as a Doornail is the fifth book in Charlaine Harris's series The Southern Vampire Mysteries.
Usage examples of "dead as a doornail".
The next time you stand and sing the National Anthem, friends and neighbors, chew on this: America is dead, dead as a doornail, dead as Jacob Marley and Buddy Holly and the Big Bopper and Harry S Truman, but the principles just propounded by Mr.
She was attractive, but her eyes were dead as a doornail from boredom.
There's a guy with a loaded rifle in his hand and four holes in his chest hanging right there in the inner fence, dead as a doornail.
You and your precious Constitution that is as dead as a doornail if we don’.
You and your precious Constitution that is as dead as a doornail if we don't get the elves off our backs?
I explained this to Featherstone, but he looked gloomy and said, ' If you ask me this case is as dead as a doornail.
The telephone operator come running out screaming bloody murder an' the copper come running down from the corner an' we both went upstairs--he paused, caught his breath--an' there was this guy Rigas, half in the bedroom and half out-, an' dead as a doornail.