autodiagnosis

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*dwóh₁
11. Proto-Indo-European*trísinflu.
12. Proto-Indo-European*dwís
13. Ancient Greekδιά (diá)
14. Ancient Greekδια- (dia-)
15. Proto-Indo-European*ǵneh₃-
16. Proto-Indo-European*ǵn̥h₃sḱéti
17. Proto-Hellenic*gignṓskō
18. Ancient Greekγῐγνώσκω (gĭgnṓskō)
19. Ancient Greekδῐαγῐγνώσκω (dĭagĭgnṓskō)
20. Ancient Greekδῐᾰ́γνωσῐς (dĭắgnōsĭs)
21. Latindiagnōsis
22. Englishdiagnosis
23. English todayautodiagnosis

From auto- + diagnosis.