Definition of Frankpledge
In old English law, a pledge or surety for freemen; that is, the pledge, or corporate responsibility, of all the inhabitants of a tithing for the general good behavior of each free-born citizen above the age of fourteen, and for his being forthcoming to answer any infraction of the law. A pledge of surety to the sovereign for the collective good conduct of a group.
That's the definition of Frankpledge in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.