autofluorescence

The story

1. Proto-Indo-European*h₂ew
2. Proto-Indo-European*tó-
3. Proto-Hellenic*autós
4. Proto-Indo-European*h₂ew
5. Ancient Greekαὖ (aû)
6. Ancient Greekτόν (tón)
7. Ancient Greekαὐτός (autós)
8. Ancient Greekαὐτο- (auto-)
9. Englishauto-
10. Proto-Indo-European*bʰel-
11. Proto-Indo-European*bʰlewH-
12. Proto-Indo-European*bʰluH-yé-ti?
13. Latinfluō
14. Latinfluor
15. Englishfluor
16. Englishfluorite
17. Middle Low Germanspar
18. Old Englishspærstān
19. Middle Englishsparston
20. Englishsparstonebf.
21. Englishspar
22. Englishfluorspar
23. Englishfluorescence
24. English todayautofluorescence

From auto- + fluorescence.