photoeccentric

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*h₁éǵʰ
9. Proto-Indo-European*h₁eǵʰs
10. Proto-Hellenic*eks
11. Ancient Greekἐκ (ek)
12. Ancient Greekἐκ- (ek-)
13. Proto-Indo-European*ḱen-?
14. Proto-Indo-European*ḱéntrom
15. Proto-Hellenic*kéntron
16. Ancient Greekκέντρον (kéntron)
17. Ancient Greekἔκκεντρος (ékkentros)
18. Medieval Latineccentricus
19. Middle Frenchexcentrique
20. Englisheccentric
21. English todayphotoeccentric

From photo- + eccentric.