Strong’s Greek
G1635 — hekon
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
ἑκών
hekon — pronounced hek-own'
of uncertain affinity; voluntary:--willingly.
2 occurrences in the KJV.
Romans 8:20
For the creature was made subject to vanity, not willingly, but by reason of him who hath subjected the same in hope,
1 Corinthians 9:17
For if I do this thing willingly, I have a reward: but if against my will, a dispensation of the gospel is committed unto me.