Middle English word proof comes from Proto-Indo-European *pro-bhwo-

Detailed word origin of proof

Dictionary entry	Language	Definition
*pro-bhwo-	Proto-Indo-European (ine-pro)
probus	Latin (lat)	(morally) upright, honest, virtuous. Good, serviceable, excellent, superior, able.
probo	Latin (lat)	I acquit, exonerate. I approve, commend. I demonstrate, prove. I test, inspect.
proba	Late Latin (LL)
prove	Old French (fro)
proof	Middle English (enm)

Words with the same origin as proof