From an apparently primary nekus (a corpse); dead (literally or figuratively; also as noun) -- dead.
a. one that has breathed his last, lifeless: Matthew 28:4; Mark 9:26; Luke 7:15; Acts 5:10; Acts 20:9; Acts 28:6; Hebrews 11:35; Revelation 1:17; ἐπί νεκροῖς, if men are dead (where death has occurred (see ἐπί, Buttmann, 2 a. ε., p. 233a at the end)), Hebrews 9:17; ἐγείρειν νεκρούς, Matthew 10:8; Matthew 11:5; Luke 7:22; hyperbolically and proleptically equivalent to as if already dead, sure to die, destined inevitably to die: τό σῶμα, Romans 8:10 (τό σῶμα and τό σωμάτιον φύσει νεκρόν, Epictetus diss. 3, 10, 15 and 3, 22, 41; in which sense Luther called the human body, although alive,einen alten Madensack (cf. Shakespeare's "thou worms-meat!")); said of the body of a dead man (so in Homer often; for נְבֵלָה a corpse Deuteronomy 28:26; Isaiah 26:19; Jeremiah 7:33; Jeremiah 9:22; Jeremiah 19:7): μετά τῶν νεκρῶν, among the dead, i. e. the buried, Luke 24:5; θάψαι τούς νεκρούς, Matthew 8:22; Luke 9:60; ὀστέα νεκρῶν, Matthew 23:27; of the corpse of a murdered man, αἷμα ὡς νεκροῦ, Revelation 16:3 (for הָרוּג, Ezekiel 37:9; for חָלָל,thrust through, slain, Ezekiel 9:7; Ezekiel 11:6).
b. deceased, departed, one whose soul is in Hades: Revelation 1:18; Revelation 2:8; νεκρός ἦν, was like one dead, as good as dead, Luke 15:24, 32; plural, 1 Corinthians 15:29; Revelation 14:13; ἐν Χριστῷ, dead Christians (see ἐν, I. 6 b., p. 211b), 1 Thessalonians 4:16; very often οἱ νεκροί and νεκροί (without the article; see Winers Grammar, p. 123 (117) and cf. Buttmann, 89 (78) note) are used of the assembly of the dead (see ἀνάστασις, 2 and ἐγείρω, 2): 1 Peter 4:6; Revelation 20:5, 12f; τίς ἀπό τῶν νεκρῶν, one (returning) from the dead, the world of spirits, Luke 16:30; ἐκ νεκρῶν, from the dead, occurs times too many to count (see ἀνάστασις, ἀνίστημι, ἐγεριω): ἀνάγειν τινα ἐκ νεκρῶν, Romans 10:7; Hebrews 13:20; ζωή ἐκ νεκρῶν, life springing forth from death, i. e. the return of the dead to life (see ἐκ, I. 5), Romans 11:15; πρωτότοκος ἐκ τῶν νεκρῶν who was the first that returned to life from among the dead, Colossians 1:18; also πρωτότοκος τῶν νεκρῶν Revelation 1:5; ζοωποίειν τούς νεκρούς Romans 4:17; ἐγείρειν τινα ἀπό τῶν νεκρῶν, to rouse one to quit (the assembly of) the dead, Matthew 14:2; Matthew 27:64; Matthew 28:7; κρίνειν ζῶντας καί νεκρούς, 2 Timothy 4:1; 1 Peter 4:5; κριτής ζώντων καί νεκρῶν, Acts 10:42; νεκρῶν καί ζώντων κυριεύειν, Romans 14:9.
c. destitute of life, without life, inanimate (equivalent to ἄψυχος): τό σῶμα χωρίς πνεύματος νεκρόν ἐστιν, James 2:26; οὐκ ἐστιν (ὁ) Θεός νεκρῶν ἀλλά ζώντων, God is the guardian God not of the dead but of the living, Matthew 22:32; Mark 12:27; Luke 20:38.
a. (spiritually dead, i. e.) "destitute of a life that recognizes and is devoted to God, because given up to trespasses and sins; inactive as respects doing right": John 5:25; Romans 6:13; Ephesians 5:14; Revelation 3:1; with τοῖς παραπτώμασιν (the dative of cause (cf. Winer's Grammar, 412 (384f))) added, Ephesians 2:1, 5; ἐν (but T Tr WH omit ἐν) τοῖς παραπτοις Colossians 2:13; in the pointed saying ἄφες τούς νεκρούς θάψαι τούς ἑαυτῶν νεκρούς, leave those who are indifferent to the salvation offered them in the gospel, to bury thee bodies of their own dead, Matthew 8:22; Luke 9:60.
b. universally, destitute of force or power, inactive, inoperative: τῇ ἁμαρτία, unaffected by the desire to sin (cf. Winers Grammar, 210 (199); Buttmann, § 133, 12), Romans 6:11; of things: ἁμαρτία, Romans 7:8; πίστις, James 2:17, 20 (R G), 26; ἔργα, powerless and fruitless (see ἔργον, 3, p. 248b bottom), Hebrews 6:1; Hebrews 9:14. (Cf. θνητός, at the end)