It all stems from the 16th century form of popular method of execution when the wrongdoer was tied to a stake and burnt to death.
These fires were known as ‘bone fires’, and in time the two words were brought together making ‘bonfire’!
We still use this term now on November 5th, Guy Fawkes night. Â Thankfully, we now only burn fake stuffed objects made of old clothes and materials.