disactivate

The story

1. Proto-Indo-European*dwóh₁
2. Proto-Indo-European*trísinflu.
3. Proto-Indo-European*d(w)is-
4. Proto-Italic*dis-
5. Latindis-
6. Old Frenchdes-
7. Latindis-
8. Middle Englishdis-
9. Englishdis-
10. Proto-Indo-European*h₂eǵ-
11. Proto-Indo-European*h₂éǵeti
12. Proto-Italic*agō
13. Latinagō
14. Ancient Greekἐνεργητικός (energētikós)
15. Latināctīvu
16. Old Frenchactif
17. Middle Englishactyf
18. Englishactive
19. Englishactivate
20. English todaydisactivate

From dis- + activate.