diester

The story

1. Proto-Indo-European*dwóh₁
2. Proto-Indo-European*dwi-
3. Proto-Hellenic*dwi-
4. Ancient Greekδῐ- (dĭ-)
5. Latindi-
6. Englishdi-
7. Proto-Indo-European*h₂eḱ-
8. Proto-Indo-European*h₂eḱéh₁yeti
9. Proto-Italic*akēō
10. Latinaceō
11. Latinacēscō
12. Latinacētum
13. Proto-West Germanic*aket
14. Proto-West Germanic*atek
15. Old High Germaneȥȥih
16. Middle High Germaneȥȥich
17. GermanEssich
18. GermanEssig
19. Proto-Indo-European*h₂eydʰ-
20. Proto-Hellenic*áitʰō
21. Ancient Greekαἴθω (aíthō)
22. Ancient Greekᾱ̓ήρ (āḗr)influ.?
23. Ancient Greekαἰθήρ (aithḗr)
24. Latinaethēr
25. GermanÄther
26. GermanEster
27. Englishester
28. English todaydiester

From di- + ester.