What is "mainpernor"

Mainpernor \Main"per*nor\, n. [OF. main hand + pernor, for preneor, a taker, F. preneur, fr. prendre to take.] (Law) A surety, under the old writ of mainprise, for a prisoner's appearance in court at a day.

Note: 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.

n. (context legal English) A surety, under the old writ of mainprise, for a prisoner's appearance in court at a day.