Source : Webster's Revised Unabridged Dictionary (1913)

Friborg \Fri"borg\, Friborgh \Fri"borgh\, n. [AS. fri?borh,
   lit., peace PLAGE; fri? peace + borh, borg, pledge, akin to
   E. borrow. The first part of the word was confused with free,
   the last part, with borough.] (Old Eng. Law)
   The pledge and tithing, afterwards called by the Normans
   frankpledge. See {Frankpledge}. [Written also {friburgh} and
   {fribourg}.] --Burril.