adj. dead·er,
dead·est 1. Having lost life; no longer alive.
2. Marked for certain death; doomed: was marked as a dead man by the assassin.
3. a. Having the physical appearance of death: a dead pallor.
b. Lacking feeling or sensitivity; numb or unresponsive: Passersby were dead to our pleas for help.
c. Weary and worn-out; exhausted.
4. a. Not having the capacity to live; inanimate or inert.
b. Not having the capacity to produce or sustain life; barren: dead soil.
5. a. No longer in existence, use, or operation.
b. No longer having significance or relevance.
c. Physically inactive; dormant: a dead volcano.
6. a. Not commercially productive; idle: dead capital.
b. Not circulating or running; stagnant: dead water; dead air.
7. a. Devoid of human or vehicular activity; quiet: a dead town.
b. Lacking all animation, excitement, or activity; dull: The party being dead, we left early.
8. Having no resonance. Used of sounds: "One characteristic of compact discs we all can hear is dead sound. It may be pure but it has no life" (Musical Heritage Review).
9. Having grown cold; having been extinguished: dead coals; a dead flame.
10. Lacking elasticity or bounce: That tennis ball is dead.
11. Out of operation because of a fault or breakdown: The motor is dead.
12. a. Sudden; abrupt: a dead stop.
b. Complete; utter: dead silence.
c. Exact; unerring. the dead center of a target.
13. Sports Out of play. Used of a ball.
14. a. Lacking connection to a source of electric current.
b. Drained of electric charge; discharged: a dead battery.
n.1. One who has died: respect for the dead.
2. The period exhibiting the greatest degree of intensity: the dead of winter; the dead of night.
adv.1. Absolutely; altogether: You can be dead sure of my innocence.
2. Directly; exactly: There's a gas station dead ahead.
3. Suddenly: She stopped dead on the stairway.
Synonyms: dead, deceased, departed, extinct, lifeless, inanimate These adjectives all mean without life.
Dead applies in general to whatever once had

but no longer has

physical life (
a dead man; a dead leaf), function (
a dead battery), or force or currency (
a dead issue; a dead language).
Deceased and
departed refer only to nonliving humans:
attended a memorial service for a recently deceased friend; looking at pictures of departed relatives. Extinct can refer to what has no living successors (
extinct species such as the dodo) or to what is extinguished or inactive (
an extinct volcano).
Lifeless applies to what no longer has physical life (
a lifeless body), to what does not support life (
a lifeless planet), or to what lacks animation, spirit, or brightness (
a lifeless performance; lifeless colors).
Inanimate is most often limited to what has never had physical life:
"The anchored gunboat simply would not sink. It evinced that unnatural stubbornness which is sometimes displayed by inanimate objects" (Stephen Crane).