Lexical Definition

‎ἀποκτείνω‎ apokteínō (ap-ok-ti'-no) to kill ^G:V
from ‎ἀπό‎ and (to slay)

put to death, kill, slay.

• to kill outright
• figuratively, to destroy

Abbott-Smith

ἀπο-κτείνω (also in late forms -κτέννω, Mt 10:28, a1., LTTr., -κτεννύω, Mk 12:5, WH), [in LXX for הרג, מוּת;]
to kill: Mt 14:5, al.; seq. instr. ἐν (q.v.), Eph 2:16, Re 2:23, al. Metaph.: Ro 7:11; τ. ἔχθραν, Eph 2:16; τὸ γράμμα ἀποκτείνει, II Co 3:6 (on the perfective force of this verb, v. M, Pr., 114).

Abbott-Smith References

Liddell-Scott-Jones

ἀποκτείνω

(later -κτέννω (which see): -κταίνω[NT]future -κτενῶ, Ionic dialect -κτενέω[Refs 5th c.BC+]: aorist 1 ἀπέκτεινα[Refs 8th c.BC+]: perfect ἀπέκτονα[Refs 5th c.BC+]; pluperfect 3rd.pers.plural -εκτόνεσαν[Refs], Ionic dialect 3rd.pers.singular -εκτόνεε[LXX+5th c.BC+]: aorist 2 -έκτᾰνον[Refs 8th c.BC+], poetry 1st pers.plural ἀπέκταμεν[Refs 8th c.BC+], infinitive -κτάμεναι, -κτάμεν, [Refs 8th c.BC+]:—passive, late (ἀποθνήσκω being used as the passive by correct writers), present in [Refs 4th c.AD+]: aorist ἀπεκτάνθην[LXX+2nd c.AD+]: aorist 2 infinitive ἀποκτανῆναι[Refs 2nd c.AD+]: perfect infinitive ἀπεκτάνθαι[LXX+2nd c.BC+]:—but aorist middle in passive sense ἀπέκτατο[Refs 8th c.BC+]; participle ἀποκτάμενος[Refs]; compare ἀποκτείνυμι:— stronger form of κτείνω, kill, slay, Epic dialect, Ionic dialect, and the prevailing form in Attic dialect (compare ἀποθνήσκω): once in [Refs 5th c.BC+]

__2 of judges, condemn to death, [Refs 5th c.BC+]; also of the accuser, [Refs 5th c.BC+]; put to death, [Refs 5th c.BC+]: generally of the law, [Refs 5th c.BC+]
__3 metaphorically, τὸ σεμνὸν ὥς μ᾽ ἀ. τὸ σόν[Refs 5th c.BC+]; σὺ μή μ᾽ ἀπόκτειν) [Refs]

_{LSJ Scripture Refs: 2Cor.3.6 ☩ LXX.1Kgs.24.12}