The story
- Proto-Indo-European*h₂eǵ-
- Proto-Indo-European*h₂éǵeti
- Proto-Italic*agō
- Latinagō
- Ancient Greekἐνεργητικός (energētikós)
- Latināctīvu
- Old Frenchactif
- Middle Englishactyf
- Englishactive
- Englishactivate
- Englishactivation
- English todayactivationist
From activation + -ist.
Etymology from Wiktionary, CC BY-SA 4.0.