dioxide

The story

1. Proto-Indo-European*dwóh₁
2. Proto-Indo-European*dwi-
3. Proto-Hellenic*dwi-
4. Ancient Greekδῐ- (dĭ-)
5. Latindi-
6. Englishdi-
7. Proto-Indo-European*h₂eḱ-der.?
8. Ancient Greekὀξύς (oxús)
9. Proto-Indo-European*ǵenh₁-
10. Proto-Indo-European*ǵénh₁os
11. Proto-Hellenic*génos
12. Ancient Greekγένος (génos)
13. Frenchoxygène
14. Proto-Indo-European*h₂eḱ-
15. Proto-Indo-European*h₂eḱéh₁yeti
16. Proto-Italic*akēō
17. Latinaceō
18. Proto-Indo-European*dʰeh₁-
19. Latinacidu
20. Frenchacide
21. Frenchoxide
22. Englishoxide
23. English todaydioxide

From di- + oxide.