episomal

The story

1. Proto-Indo-European*h₁ep-
2. Proto-Indo-European*h₁éps
3. Proto-Indo-European*h₁épi
4. Proto-Hellenic*epí
5. Ancient Greekἐπί (epí)
6. Ancient Greekἐπῐ- (epĭ-)
7. Englishepi-
8. Proto-Indo-European*tewh₂-
9. Proto-Indo-European*twoH-mn̥
10. Proto-Hellenic*twṓmə?
11. Proto-Indo-European*styeH-
12. Proto-Indo-European*(s)tyoH-mn̥
13. Proto-Hellenic*styṓmə?
14. Ancient Greekσῶμα (sôma)
15. Englishepisome
16. Proto-Indo-European*h₂el-
17. Proto-Indo-European*h₂élisder.?
18. English todayepisomal

From episome + -al.