cyclononane

The story

1. Proto-Indo-European*kʷelh₁-redup.
2. Proto-Indo-European*kʷékʷlos
3. Proto-Hellenic*kʷókʷlos
4. Proto-Hellenic*kúklos
5. Ancient Greekκύκλος (kúklos)
6. Late Latincyclus
7. Middle Englishcicle
8. Englishcycle
9. Ancient Greekκύκλος (kúklos)
10. Ancient Greekκυκλῐκός (kuklĭkós)
11. Classical Latincyclicu
12. Middle Frenchcyclique
13. Frenchcyclique
14. Classical Latincyclicus
15. Englishcyclic
16. Englishcyclo-
17. Proto-Indo-European*h₁néwn̥
18. Proto-Indo-European*h₁newn̥(n)ós
19. Proto-Italic*nowenos
20. Latinnōnus
21. Englishnon-
22. Englishnonane
23. English todaycyclononane

From cyclo- + nonane.