bonfire

the word 'bonfire' has a deceptively simple origin. it comes from the middle english 'bonefire', literally a 'fire of bones'. this referred to the historical practice of burning bones, often of slaughtered animals, as a means of disposal or during specific celebrations. over time, the spelling shifted from 'bonefire' to 'bonfire', obscuring the original 'bone' element. the meaning broadened from a fire for burning bones to any large outdoor fire, particularly one for burning rubbish or as the centerpiece of a communal gathering, thus losing its direct compositional logic.

this is a simplex word. its spelling and meaning derive from a historical compound in middle english, but its modern form is not productively divisible into separate, meaningful morphemes for a learner.