autohemagglutination

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. Englishhem-
11. Frenchagglutination
12. Proto-Indo-European*h₂éd
13. Proto-Italic*ad
14. Proto-Italic*ad-
15. Latinad-
16. Proto-Indo-European*gleyH-
17. Proto-Indo-European*glóh₁ytn̥
18. Proto-Italic*gloiten
19. Latinglūten
20. Latinglūtinō
21. Latinagglūtinō
22. New Latinagglutinatio
23. Englishagglutination
24. Englishhemagglutination
25. English todayautohemagglutination

From auto- + hemagglutination.