Strong's G4258 — προαμαρτάνω (verb)
proamartano (pro-am-ar-tan'-o) v.
1. to sin previously (to conversion)
[from G4253 and G264]
KJV: sin already, heretofore sin 
Root(s): G4253, G264 
Hebrew root: ἁμαρτάνω
Occurrences: 2