autoactivity

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*h₂eǵ-
11. Proto-Indo-European*h₂éǵeti
12. Proto-Italic*agō
13. Latinagō
14. Ancient Greekἐνεργητικός (energētikós)
15. Latināctīvus
16. Latināctīvitās
17. Middle Frenchactivité
18. Englishactivity
19. English todayautoactivity

From auto- + activity.