τεκμήριον G5039
tekmḗrion · tek-may'-ree-on · Noun Neuter
neuter of a presumed derivative of (a goal or fixed limit); a token (as defining a fact), i.e. criterion of certainty:--infallible proof.
1 Occurrence in the King James Bible
Acts 1:3To whom also he shewed himself alive after his passion by many infallible proofs, being seen of them forty days, and speaking of the things pertaining to the kingdom of God: