Lexical Definition

‎ἑκών‎ hekṓn (hek-own') voluntarily ^G:A
of uncertain affinity

willingly.

• voluntary

Abbott-Smith

ἑκών, -οῦσα, -όν [in LXX: Ex 21:13, Jb 36:19 * ;]
willing, of one's own free will: Ro 8:20, I Co 9:17 (Cremer, 246).†

Abbott-Smith References

Liddell-Scott-Jones

ἑκών, ἑκοῦσα, ἑκόν:

(ϝέκ- [Refs]; cf. Sanskrit váśmi 'wish'):—readily, [ἑκών [prev. author] “OC” 935 ">Refs 8th c.BC+]; ἑ. παρ᾽ ἑκόντος λαμβάνειν, i.e. by mutual consent, [Refs 4th c.BC+]

__2 wittingly, purposely, ἑκὼν δ᾽ ἡμάρτανε φωτός [Refs 8th c.BC+]
__3 in Attic dialect Prose [Refs 2nd c.AD+] as far as depends on one's will, as far as concerns one, with a negative, [Refs 5th c.BC+]; also in oblique cases, ὑπὸ σοῦ ἑκόντος εἶναι [Refs]; or in a sentence implying a negative, θαυμάζοιμεν ἂν εἰ.. τις ἑκὼν εἶναι (perhaps delendum).. ἀφικνεῖτα; [Refs 5th c.BC+]
__II rarely of things, κακὰ ἑ. κοὐκ ἄκοντα [Refs 5th c.BC+]
__III for adverb see ἑκοντήν, ἑκοντί: regular adverb ἑκόντως is uncertain in [Refs 2nd c.AD+]