autoerotic

The story

1. Proto-Indo-European*h₂ew
2. Proto-Indo-European*tó-
3. Proto-Hellenic*autós
4. Proto-Indo-European*h₂ew
5. Ancient Greekαὖ (aû)
6. Ancient Greekτόν (tón)
7. Ancient Greekαὐτός (autós)
8. Ancient Greekαὐτο- (auto-)
9. Englishauto-
10. Proto-Indo-European*h₁rem-
11. Proto-Indo-European*h₁rém-e-tider.?
12. Ancient Greekἐράω (eráō)
13. Ancient Greekἔρως (érōs)
14. Ancient Greekἐρωτῐκός (erōtĭkós)
15. Latinerōticu
16. Frenchérotique
17. Englisherotic
18. English todayautoerotic

From auto- + erotic.