nonionic

The story

1. Proto-Indo-European*né
2. Proto-Germanic*ne
3. Proto-Indo-European*ís?
4. Proto-Indo-European*h₁óynos
5. Proto-Germanic*ainaz
6. Proto-Germanic*nainaz
7. Proto-West Germanic*nain
8. Old Englishnān
9. Middle Englishnon
10. Old Englishnān
11. Old Englishnān-
12. Middle Englishnon-
13. Englishnon-
14. Proto-Indo-European*h₁ey-
15. Proto-Indo-European*h₁éyti
16. Proto-Hellenic*éimi
17. Ancient Greekἰόν (ión)
18. Englishion
19. Englishionic
20. English todaynonionic

From non- + ionic.