wintard

The story

1. Proto-Indo-European*h₂weh₁-
2. Proto-Indo-European*h₂wḗh₁ti
3. Proto-Indo-European*h₂wéh₁n̥ts
4. Proto-Germanic*windaz
5. Old Norsevindr
6. Proto-Indo-European*h₃ekʷ-
7. Proto-Germanic*augô
8. Proto-Norse*ᚨᚢᚷᚨ (*auga)
9. Old Norseauga
10. Old Norsevindauga
11. Middle Englishwyndowe
12. Englishwindow
13. EnglishWindows
14. Proto-Italic*wre-
15. Latinre-
16. Proto-Indo-European*terh₂-
17. Proto-Indo-European*tr̥h₂dos
18. Proto-Italic*tardos
19. Latintardus
20. Latinretardō
21. Anglo-Normanretarder
22. Middle Englishretarden
23. Englishretard
24. English todaywintard

From Windows + -tard.