polyfluoroalkyl

The story

1. Proto-Indo-European*pleh₁-
2. Proto-Indo-European*polh₁ús
3. Ancient Greekπολῠ́ς (polŭ́s)
4. Englishpoly-
5. Proto-Indo-European*bʰel-
6. Proto-Indo-European*bʰlewH-
7. Proto-Indo-European*bʰluH-yé-ti?
8. Latinfluō
9. Latinfluor
10. Englishfluor
11. Englishfluorite
12. Middle Low Germanspar
13. Old Englishspærstān
14. Middle Englishsparston
15. Englishsparstonebf.
16. Englishspar
17. Englishfluorspar
18. Englishfluorescencebf.
19. Englishfluoresce
20. Englishfluor(escent)
21. Latinō
22. Old Frenchoh
23. Middle Englisho
24. EnglishO
25. Middle Englisho
26. Englishoh
27. Englishfluoro
28. Englishpolyfluoro
29. Akkadian𒎎𒋆𒁉𒍣𒁕 (guḫlum)
30. Aramaicכוחלא (kuḥlā)
31. Arabicكُحْل (kuḥl)
32. Andalusian Arabicكُحُول (kuḥūl)
33. Medieval Latinalcoho
34. Middle Englishalcofol
35. Englishalc(ohol)
36. Proto-Indo-European*swel-der.?
37. Ancient Greekῡ̔́λη (hū́lē)
38. Englishalkyl
39. English todaypolyfluoroalkyl

From polyfluoro + alkyl, equivalent to poly- + fluoro- + alkyl.