ultramicroscopical

The story

1. Proto-Indo-European*h₂el-
2. Latinūls
3. Latinultrā
4. Englishultra-
5. Proto-Indo-European*mey-der.?
6. Ancient Greekμῑκρός (mīkrós)
7. Proto-Indo-European*speḱ-
8. Proto-Indo-European*spéḱyeti
9. Proto-Hellenic*sképt͏̌omai
10. Ancient Greekσκέπτομαι (sképtomai)
11. Ancient Greekσκοπός (skopós)
12. Ancient Greekσκοπέω (skopéō)
13. Latinmīcroscopium
14. Italianmicroscopio
15. Englishmicroscope
16. Proto-Indo-European*h₂el-
17. Proto-Indo-European*h₂élisder.?
18. Englishmicroscopical
19. English todayultramicroscopical

From ultra- + microscopical.