a large open-air fire used for burning rubbish or as part of a celebration:the smell of burning leaves from a garden bonfire figurativeyet again, events had made a bonfire of her plans
late Middle English: from bone+ fire. The term originally denoted a large open-air fire on which bones were burnt (sometimes as part of a celebration), also one for burning heretics or proscribed literature. Dr Johnson accepted the mistaken idea that the word came from French bon 'good'
bonfire in other Oxford dictionaries
Definition of bonfire in the US English dictionary