unsocial

The story

1. Proto-Indo-European*né
2. Proto-Indo-European*n̥-
3. Proto-Germanic*un-
4. Proto-West Germanic*un-
5. Old Englishun-
6. Middle Englishun-
7. Englishun-
8. Proto-Indo-European*sekʷ-
9. Proto-Indo-European*sokʷéh₂
10. Proto-Indo-European*sokʷh₂ṓy
11. Proto-Indo-European*sokʷyós
12. Proto-Italic*sokjos
13. Latinsokios
14. Latinsocius
15. Proto-Indo-European*h₂el-
16. Proto-Indo-European*h₂élisder.?
17. Latinsociāli
18. Middle Frenchsocia
19. Englishsocial
20. English todayunsocial

From un- + social.