from
The Collaborative International Dictionary of English v.0.48
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.
[1913 Webster]
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.
[1913 Webster]