cidiot

The story

1. Proto-Indo-European*ḱey-
2. Proto-Italic*keiwis
3. Latinceivis
4. Latinceivitās
5. Late Latincīvitātem (city)
6. Old Frenchcitet
7. Middle Englishcite
8. Englishcity
9. Proto-Indo-European*swé
10. Proto-Indo-European*swéd-yo-s
11. Proto-Hellenic*hwédios
12. Ancient Greekἴδιος (ídios)
13. Ancient Greekἰδιώτης (idiṓtēs)
14. Latinidiota
15. Old Frenchidiote
16. Middle Englishydiote
17. Englishidiot
18. English todaycidiot

Blend of city + idiot.