phytosteroid

The story

1. Proto-Indo-European*bʰuH-
2. Proto-Indo-European*bʰuHyéti
3. Ancient Greekφῠ́ω (phŭ́ō)
4. Ancient Greekφῠτός (phŭtós)
5. Ancient Greekφῠτόν (phŭtón)
6. Englishphyto-
7. Proto-Indo-European*ǵʰelh₃-
8. Proto-Hellenic*kʰolā́
9. Ancient Greekχολή (kholḗ)
10. Proto-Indo-European*ster-
11. Ancient Greekστερεός (stereós)
12. Frenchcholestérine
13. Frenchcholestéro
14. Englishcholesterol
15. Englishsterol
16. Proto-Indo-European*weyd-
17. Proto-Indo-European*wéydos
18. Proto-Hellenic*wéidos
19. Ancient Greekεἶδος (eîdos)
20. Englishsteroid
21. English todayphytosteroid

From phyto- + steroid.