dead

dead blessed are the dead that the rain rains on proverbial saying, early 17th century; a similar belief to that in, happy is the bride that the sun shines on.
dead cat bounce a misleading sign of vitality in something that is really moribund. A dead cat will not bounce, although if dropped from a sufficient height it might appear to do so. The expression was coined in the late 20th century by Wall Street traders for the situation when a stock or company on a long-term, irrevocable downward trend suddenly shows a small temporary improvement.
dead in the water unable to function effectively. Originally used of a ship, meaning ‘unable to move’.
dead letter box a place where messages can be left and collected without the sender and recipient meeting.
deadline historical term for a line drawn around a prison, beyond which prisoners were liable to be shot.
dead man walking in the United States, a condemned prisoner making the final journey to the execution chamber.
dead meat used to suggest that someone is in serious trouble.
dead men don't bite proverbial saying, mid 16th century, meaning that killing an enemy puts an end to danger. According to Plutarch, the words ‘a dead man does not bite’ were used by Theodotus, a teacher of rhetoric, in advising the Egyptians to murder Pompey the Great when he sought refuge in Egypt after his defeat at Pharsalia in 48 bc. A similar story is told of Patrick, Lord Gray (d. 1612), who when pressing for the execution of Mary Queen of Scots in 1587, said, ‘A dead woman bites not.’
dead men tell no tales often used to imply that a person's knowledge of a secret will die with them. The saying is recorded from the mid 17th century, but a source from the mid 16th century has, ‘He that hath his body laden with meat and drink is no more meet to pray to God then a dead man is to tell a tale.’
dead white European male a writer, philosopher, or other significant figure whose importance and talents may have been exaggerated by virtue of his belonging to a historically dominant gender and ethnic group. The acronym DWEM is also used.
let the dead bury the dead proverbial saying, early 19th century, often used to mean that the past should be left undisturbed; with ultimate biblical allusion to Matthew 8:22, ‘Jesus said unto him, Follow me, and let the dead, bury their dead.’

See also Dead Sea, as dead as a doornail, it's ill waiting for dead men's shoes, Queen Anne is dead at queen, the quick and the dead, never speak ill of the dead.