unaccusativity

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*h₂éd
9. Proto-Italic*ad
10. Proto-Italic*ad-
11. Latinad-
12. Proto-Italic*kaussā
13. Old Latincaussa
14. Latincausa
15. Latinaccūsō
16. Ancient Greekαἰτῐᾱτῐκή (aitĭātĭkḗ)
17. Latinaccūsātīvus
18. Anglo-Normanaccusatif
19. Latinaccūsātīvus
20. Middle Frenchacusatif
21. Latinaccūsātīvus
22. Middle Englishaccusative
23. Englishaccusative
24. English todayunaccusativity

From un- + accusative + -ity.