\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.
(b) The tithing itself. --Bouvier.
          The servants of the crown were not, as now, bound
          in frankpledge for each other.       --Macaulay.