A language which no longer has any native speakers, particularly (archaic) Latin and Ancient Greek.

(of a body of water) Completely still with no waves and no wind.

(nautical) The condition of a perfectly flat sea with no waves and no wind.

(idiomatic) Something that discloses, usually unintentionally, a fact or an intention.

(medicine, law) In a state in which usual medically observable vital signs—such as respiration, heartbeat, and corneal reflex—are not present, but from which patients are sometimes revived.

Alternative spelling of deadborn

(US, idiomatic) With sufficient evidence to establish responsibility definitively.

(idiomatic) Utterly dead.

plural of dead ball

(uncountable, idiomatic, management) Personnel no longer contributing to an organization. / Used other than figuratively or idiomatically: see dead, wood.