Probator
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
In old English law
Strictly, an accomplice in felony who to save himself confessed the fact, and charged or accused any other as principal or accessory, against whom he was bound to make good his charge. It also signified an approver or one who undertakes to prove a crime charged upon another.
Jacob. See State v. Graham, 41 N. J. Law, 16, 32 Am. Rep. 174.