unfantastical

The story

1. Proto-Indo-European*né
2. Proto-Indo-European*n̥-
3. Proto-Germanic*un-
4. Proto-West Germanic*un-
5. Old Englishun-
6. Middle Englishun-
7. Englishun-
8. Proto-Indo-European*bʰeh₂-
9. Proto-Indo-European*bʰh₂nyéti
10. Proto-Hellenic*pʰáňňō
11. Ancient Greekφαίνω (phaínō)
12. Ancient Greekφαντάζω (phantázō)
13. Ancient Greekφανταστικός (phantastikós)
14. Late Latinphantasticus
15. Middle Frenchfantastique
16. Englishfantastic
17. Proto-Indo-European*h₂el-
18. Proto-Indo-European*h₂élisder.?
19. Englishfantastical
20. English todayunfantastical

From un- + fantastical.