The story
- Proto-Indo-European*dewh₂-der.?
- Proto-Italic*dwenos
- Old Latinduonus
- Latinbonus
- Old Frenchbon
- Middle Frenchbon
- Frenchbonredup.
- Frenchbonbon
- English todaybonbon
Borrowed from French bonbon, reduplication of bon (“good”).
Etymology from Wiktionary, CC BY-SA 4.0.