cyclodehydrogenation

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*de
18. Proto-Indo-European*déh₁
19. Proto-Italic*dē
20. Latindē
21. Latindē-
22. Englishde-
23. Proto-Indo-European*wed-
24. Proto-Indo-European*wódr̥
25. Proto-Hellenic*údōr
26. Ancient Greekῡ̆̔́δωρ (hū̆́dōr)
27. Ancient Greekὑδρο- (hudro-)
28. Frenchhydro-
29. Proto-Indo-European*ǵenh₁-
30. Proto-Indo-European*ǵénh₁os
31. Proto-Hellenic*génos
32. Ancient Greekγένος (génos)
33. Frenchhydrogène
34. Englishhydrogen
35. Englishhydrogenation
36. Englishdehydrogenation
37. English todaycyclodehydrogenation

From cyclo- + dehydrogenation.