hexoxide

The story

1. Proto-Indo-European*swéḱs
2. Proto-Hellenic*hwéks
3. Ancient Greekἕξ (héx)
4. Ancient Greekἑξα- (hexa-)
5. Latinhexa-
6. Englishhexa-
7. Englishhex-
8. Proto-Indo-European*h₂eḱ-der.?
9. Ancient Greekὀξύς (oxús)
10. Proto-Indo-European*ǵenh₁-
11. Proto-Indo-European*ǵénh₁os
12. Proto-Hellenic*génos
13. Ancient Greekγένος (génos)
14. Frenchoxygène
15. Proto-Indo-European*h₂eḱ-
16. Proto-Indo-European*h₂eḱéh₁yeti
17. Proto-Italic*akēō
18. Latinaceō
19. Proto-Indo-European*dʰeh₁-
20. Latinacidu
21. Frenchacide
22. Frenchoxide
23. Englishoxide
24. English todayhexoxide

From hex- + oxide.