Strong’s Greek
G1596 — hekousios
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
ἑκουσίως
hekousios — pronounced hek-oo-see'-ose
adverb from the same as 1595; voluntarily:--wilfully, willingly. see GREEK for 1595
2 occurrences in the KJV.
Hebrews 10:26
For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins,
1 Peter 5:2
Feed the flock of God which is among you, taking the oversight thereof, not by constraint, but willingly; not for filthy lucre, but of a ready mind;