frankpledge
Any group so similarly answerable for the conduct of all its members and liable for collective punishment.
The servants of the Crown were not, as now, bound in frankpledge for each other.
A decener: a member of a tithing bound in frankpledge.
historical
Entire vills sir Henry Spelman conjectures to have consisted of ten freemen, or frank-pledges.
The tithing itself.
historical, uncommon
Where it comes from
From Anglo-Latin franciplegium, a Latinization of Anglo-Norman frauncplege ("free pledge"), a mistranslation of Old English friðborh ("pledge of peace"), which had the corrupted form friborh, which led to the Modern English term friborg, as if it were *freoborh ("free pledge"). See also friborg, which refers to the predecessor of frankpledge.
Adapted from the Wiktionary entry frankpledge (CC BY-SA 4.0).