The story
- Proto-Indo-European*kap-?
- Proto-Indo-European*kap-
- Proto-Indo-European*káput
- Proto-Italic*kaput
- Latincaput
- Latincapitulum
- Proto-Indo-European*h₂el-
- Proto-Indo-European*h₂élisder.?
- Latincapitulāre?
- Late Latincappa
- Old Frenchcape
- Old Frenchcapote
- Frenchcapot
- Germankaputt
- Englishkaput
- Englishpoof
- English todaykapoof
Blend of kaput + poof. Perhaps influenced by the ka- prefix (which is a variant of ker-).
Etymology from Wiktionary, CC BY-SA 4.0.