The earliest recorded uses of the word Bonfire date back to the late 15th century, with the Catholicon Anglicum spelling it as banefyre and John Mirk's Book of Festivals speaking of a communal fire in celebrations of Saint John's Eve that "was clene bones & no wode & that is callid a bone fyre". The word is thus a compound of "bone" and "fire.
Reference: The visit of President Nicolae Ceauşescu together with Elena Ceauşescu and other party and state leaders to the Fair of samples and consumer goods at the Exhibition Complex in Piaţa Scânteii. (20.VIII.1977)