Definition from Wiktionary, the free dictionary
- (figuratively, humorous) comparative form of : more dead; or at least more evidently dead.
- He was deader than a dead dog's bone buried down a blind alley off a dead-end street in a ghost town. Man, he was dead.
- 1920, Edgar Rice Burroughs, Tarzan the Untamed 
- Oldwick drew the pistol from his shirt. "If he has made up his mind to kill me," he thought. "I can't see that it will make any difference in the long run whether I infuriate him or not. The beggar can't kill me any deader in one mood than another."
- 1920, Sinclair Lewis, Main Street 
- The days of pioneering, of lassies in sunbonnets, and bears killed with axes in piney clearings, are deader now than Camelot...
deader (plural deaders)
- (figurative or humorous, informal) One who is deceased, or will shortly become so.
- I could tell he was a deader by the way his eyes were glazed over; there was no life left in those eyes.
- 1887, Arthur Conan Doyle, A Study in Scarlet 
- "No, nor drink. And Mr. Bender, he was the fust to go, and then Indian Pete, and then Mrs. McGregor, and then Johnny Hones, and then, dearie, your mother."
- "Then mother's a deader too," cried the little girl, dropping her face in her pinafore and sobbing bitterly.
- "Yes, they all went except you and me...