Frank"pledge` (?), n. [Frank free + pledge.] O. Eng.Law (a)
A pledge or surety for the good behavior of freemen, -- each freeman who was a member of an ancient decennary, tithing, or friborg, in England, being a pledge for the good conduct of the others, for the preservation of the public peace; a free surety
The tithing itself
The servants of the crown were not, as now, bound in frankpledge for each other.
© Webster 1913.