Meaning

noun a large outdoor fire that is lighted as a signal or in celebration

originPIE word *péh₂wr̥ From Middle English bonnefyre (“a fire in which bones are burnt, bonfire”) [and other forms], by surface analysis, bone + fire. Replaced earlier Middle English bale-fyre, from Old English bǣlfȳr (see balefire). The Oxford English Dictionary (OED) notes that bonfires, originally lit as part of midsummer celebrations, were not generally associated with the burning of bones.…

Etymology from Wiktionary, CC BY-SA 3.0