infallible proof

Strong’s Dictionary of Greek Words:

Greek:
τεκμήριον
Transliteration:
tekmerion
Phonic:
tek-may’-ree-on
Meaning:
neuter of a presumed derivative of τεκμάρ (a goal or fixed limit); a token (as defining a fact), i.e. criterion of certainty
KJV Usage:
infallible proof