heteroactivate

The story

1. Proto-Indo-European*sem-
2. Proto-Indo-European*sḿ̥teros
3. Proto-Hellenic*hə́teros
4. Ancient Greekἕτερος (héteros)
5. Englishhetero-
6. Proto-Indo-European*h₂eǵ-
7. Proto-Indo-European*h₂éǵeti
8. Proto-Italic*agō
9. Latinagō
10. Ancient Greekἐνεργητικός (energētikós)
11. Latināctīvu
12. Old Frenchactif
13. Middle Englishactyf
14. Englishactive
15. Englishactivate
16. English todayheteroactivate

From hetero- + activate.