autodiagnostic

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. Ancient Greekδῐᾰ- (dĭă-)
22. Proto-Indo-European*ǵneh₃-
23. Proto-Indo-European*ǵneh₃tis
24. Ancient Greekγνῶσις (gnôsis)
25. Ancient Greekγνωστῐκός (gnōstĭkós)
26. Ancient Greekδῐαγνωστῐκός (dĭagnōstĭkós)
27. Englishdiagnostic
28. English todayautodiagnostic

From auto- + diagnostic.