IDIOMS

stone dead

(idiomatic) Utterly dead.

Example: 1969, Monty Python, "Monty Python’s Flying Circus" (Dead Parrot sketch)
  [Owner]: No no he's not dead, he's, he's restin'! Remarkable bird, the Norwegian Blue, idn'it, ay? Beautiful plumage!
  [Mr. Praline]: The plumage don't enter into it. It's stone dead.