Strong’s Greek
G4258 — proamartano
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
προαμαρτάνω
proamartano — pronounced pro-am-ar-tan'-o
from 4253 and 264; to sin previously (to conversion):--sin already, heretofore sin. see GREEK for 4253 see GREEK for 264
2 occurrences in the KJV.
2 Corinthians 12:21
And lest, when I come again, my God will humble me among you, and that I shall bewail many which have sinned already, and have not repented of the uncleanness and fornication and lasciviousness which they have committed.
2 Corinthians 13:2
I told you before, and foretell you, as if I were present, the second time; and being absent now I write to them which heretofore have sinned, and to all other, that, if I come again, I will not spare: