Literal:
* Dead to the world: Sleeping soundly
* Dead silence: Complete silence
* Dead weight: A useless or burdensome person or thing
* Dead end: A situation with no way forward
* Dead reckoning: Navigating without using instruments
* Dead letter: A law or rule that is no longer enforced
Figurative:
* Dead tired: Extremely tired
* Dead broke: Having no money
* Dead set against something: Strongly opposed
* Dead wrong: Completely mistaken
* Dead giveaway: An obvious sign
* Deadbeat: Someone who doesn't pay their debts
* Dead ringer: Someone who looks or sounds exactly like someone else
* Dead in the water: A plan or project that has failed
* Dead to rights: Caught in the act
* Dead serious: Completely serious
* Deadpan: A facial expression with no emotion
* Dead heat: A tie in a race
* Dead of night: The darkest and quietest part of the night
* Dead center: Exactly in the middle
* Dead air: Silence on a radio or TV broadcast
* Dead as a doornail: Completely dead
* The dead of winter: The coldest part of winter
Idioms:
* Beat (someone) to death: To talk about something endlessly
* Die laughing: To laugh very hard
* Dead as a dodo: Extinct or obsolete
* Dead men tell no tales: A person who is dead cannot reveal secrets
* The dead can't speak: The dead cannot offer testimony
* Give up the ghost: To die
* The ghost of a chance: A very small chance
* Dead as a disco: Outdated
* A dead loss: A complete failure
This is not an exhaustive list, but it gives you a good starting point for exploring phrases and idioms containing the word "dead."