Source : Webster's Revised Unabridged Dictionary (1913)

Bullbeggar \Bull"beg`gar\, n.
   Something used or suggested to produce terror, as in children
   or persons of weak mind; a bugbear.

         And being an ill-looked fellow, he has a pension from
         the church wardens for being bullbeggar to all the
         forward children in the parish.          --Mountfort
                                                  (1691).