multiactivity

The story

1. Proto-Indo-European*mel-
2. Proto-Indo-European*ml̥tós?
3. Proto-Italic*moltos
4. Latinmultus
5. Latinmultī
6. Middle Englishmulti-
7. Englishmulti-
8. Proto-Indo-European*h₂eǵ-
9. Proto-Indo-European*h₂éǵeti
10. Proto-Italic*agō
11. Latinagō
12. Ancient Greekἐνεργητικός (energētikós)
13. Latināctīvus
14. Latināctīvitās
15. Middle Frenchactivité
16. Englishactivity
17. English todaymultiactivity

From multi- + activity.