prognostically

The story

1. Proto-Indo-European*per-der.?
2. Proto-Indo-European*pér
3. Proto-Indo-European*pró
4. Ancient Greekπρό (pró)
5. Ancient Greekπρο- (pro-)
6. Proto-Indo-European*ǵneh₃-
7. Proto-Indo-European*ǵneh₃tis
8. Ancient Greekγνῶσις (gnôsis)
9. Ancient Greekγνωστῐκός (gnōstĭkós)
10. Ancient Greekπρο- (pro-)
11. Ancient Greekγνῶσῐς (gnôsĭs)
12. Ancient Greekπρόγνωσῐς (prógnōsĭs)
13. Ancient Greekπρογνωστῐκός (prognōstĭkós)
14. Medieval Latinprognosticus
15. Englishprognostic
16. Proto-Indo-European*h₂el-
17. Proto-Indo-European*h₂élisder.?
18. Proto-Indo-European*leyg-
19. Proto-Germanic*līką
20. English todayprognostically

From prognostic + -ally.