nonmicroscopical

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*mey-der.?
15. Ancient Greekμῑκρός (mīkrós)
16. Proto-Indo-European*speḱ-
17. Proto-Indo-European*spéḱyeti
18. Proto-Hellenic*sképt͏̌omai
19. Ancient Greekσκέπτομαι (sképtomai)
20. Ancient Greekσκοπός (skopós)
21. Ancient Greekσκοπέω (skopéō)
22. Latinmīcroscopium
23. Italianmicroscopio
24. Englishmicroscope
25. Proto-Indo-European*h₂el-
26. Proto-Indo-European*h₂élisder.?
27. Englishmicroscopical
28. English todaynonmicroscopical

From non- + microscopical.