Strong's G544 — ἀπειθέω (verb)
apeitheo (ap-ei-theh'-o) v.
1. to disbelieve (wilfully and perversely)
[from G545]
KJV: not believe, disobedient, obey not, unbelieving 
Root(s): G545 
Hebrew root: ἀπειθής
Occurrences: 14