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]