Mainprise

A writ directed to the sheriff, commanding him to take sureties, called mainpernors, for the prisoner's appearance, and to let him go at large. This writ is now obsolete.

Deliverance of a prisoner on security for his appearance at a day.

To suffer to go at large, on his finding sureties, or mainpernors, for his appearance at a day; -- said of a prisoner.