nonmystically

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*mewH-
15. Proto-Indo-European*mewH-ye-
16. Ancient Greekμῡ́ω (mū́ō)
17. Ancient Greekμῠέω (mŭéō)
18. Ancient Greekμῠ́στης (mŭ́stēs)
19. Ancient Greekμῠστῐκός (mŭstĭkós)
20. Latinmysticus
21. Old Frenchmistique
22. Englishmystic
23. Proto-Indo-European*h₂el-
24. Proto-Indo-European*h₂élisder.?
25. Englishmystical
26. Englishnonmystical
27. English todaynonmystically

From nonmystical + -ly.