superproper

The story

1. Proto-Indo-European*úp
2. Proto-Indo-European*upér
3. Proto-Italic*super
4. Latinsuper
5. Latinsuper-
6. Englishsuper-
7. Proto-Indo-European*per-der.?
8. Proto-Indo-European*pér
9. Proto-Indo-European*pró
10. Proto-Indo-European*pro-
11. Proto-Italic*pro-
12. Proto-Indo-European*preyH-
13. Proto-Indo-European*priHós
14. Proto-Italic*prijos
15. Proto-Italic*proprijos
16. Latinpropriu
17. Anglo-Normanpropre
18. Middle Englishpropre
19. Englishproper
20. English todaysuperproper

From super- + proper.