1. dead as a doornail - Adjective
2. dead as a doornail - Phrase
dead as a doornail
(simile) Unquestionably dead. Used for both inanimate objects and once living beings.
I picked up the phone, but the line was dead as a doornail.
We finally found John's cat run over in the next road. He was as dead as a doornail.
Mind! I don’t mean to say that I know, of my own knowledge, what there is particularly dead about a door-nail. I might have been inclined, myself, to regard a coffin-nail as the deadest piece of ironmongery in the trade. But the wisdom of our ancestors is in the simile; and my unhallowed hands shall not disturb it, or the Country’s done for. You will therefore permit me to repeat, emphatically, that Marley was as dead as a door-nail.