Emily Dickinson Lexicon

MAIN-PERN'OR, n. [Old Fr. main, the hand, and prendre, to take; pernon, pernez, for prenon, prenez.]

In law, a surety for a prisoner's appearance in court at a day. Mainpernors differ from bail, in that a man's bail may imprison or surrender him before the stipulated day of appearance; mainpernors can do neither; they are bound to produce him to answer all charges whatsoever. Blackstone.