superoxide

The story

1. Proto-Indo-European*úp
2. Proto-Indo-European*upér
3. Proto-Italic*super
4. Latinsuper
5. Latinsuper-
6. Englishsuper-
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. Latinacidu
15. Frenchacide
16. Frenchoxide
17. Englishoxide
18. English todaysuperoxide

From super- + oxide.