transcompartmental

The story

1. Proto-Indo-European*terh₂-
2. Proto-Indo-European*térh₂t
3. Proto-Indo-European*tr̥h₂ónts
4. Proto-Indo-European*tr̥h₂n̥ts
5. Proto-Italic*trāns
6. Proto-Italic*trāns-
7. Latintrans-
8. Englishtrans-
9. Proto-Indo-European*ḱe?
10. Proto-Indo-European*ḱóm
11. Proto-Italic*kom
12. Proto-Italic*kom-
13. Latincom-
14. Proto-Indo-European*perh₃-
15. Proto-Indo-European*pérh₃tis?
16. Proto-Italic*partis
17. Latinpars
18. Latinpartiō
19. Latinpartior
20. Latincompartīrī
21. Italiancompartire
22. Italiancompartimento
23. Middle Frenchcompartiment
24. Englishcompartment
25. Proto-Indo-European*h₂el-
26. Proto-Indo-European*h₂élisder.?
27. Englishcompartmental
28. English todaytranscompartmental

From trans- + compartmental.