photospectroscopically

The story

1. Proto-Indo-European*bʰeh₂-
2. Proto-Indo-European*bʰéh₂os
3. Proto-Hellenic*pʰáwos
4. Ancient Greekφᾰ́ος (phắos)
5. Ancient Greekφῶς (phôs)
6. Ancient Greekφωτο- (phōto-)
7. Englishphoto-
8. Proto-Indo-European*speḱ-
9. Proto-Indo-European*spéḱyeti
10. Proto-Italic*spekjō
11. Latinspeciō
12. Latinspectrum
13. Englishspectrum
14. Englishspectro-
15. Proto-Indo-European*spéḱyeti
16. Proto-Hellenic*sképt͏̌omai
17. Ancient Greekσκέπτομαι (sképtomai)
18. Ancient Greekσκοπός (skopós)
19. Ancient Greekσκοπέω (skopéō)
20. Latinspectrum
21. Frenchspectro-
22. Ancient Greekσκοπέω (skopéō)
23. Frenchspectroscopie
24. Frenchspectroscopique
25. Englishspectroscopic
26. Proto-Indo-European*h₂el-
27. Proto-Indo-European*h₂élisder.?
28. Proto-Indo-European*leyg-
29. Proto-Germanic*līką
30. Englishspectroscopically
31. English todayphotospectroscopically

From photo- + spectroscopically.