xylopyranose

The story

1. Proto-Indo-European*kes-
2. Proto-Indo-European*ksewlo-der.?
3. Ancient Greekξῠ́λον (xŭ́lon)
4. Englishxylo-
5. Proto-Indo-European*péh₂wr̥
6. Proto-Hellenic*pāwər
7. Ancient Greekπῦρ (pûr)
8. Ancient Greekπυρά (purá)
9. Latinpyra
10. Englishpyre
11. Englishpyran
12. Proto-Hellenic*dléukus?
13. Ancient Greekγλεῦκος (gleûkos)
14. Frenchglucose
15. Englishglucosebf.
16. Englishpyranose
17. English todayxylopyranose

From xylo- + pyranose.