antiterrorism

The story

1. Proto-Indo-European*h₂ent-
2. Proto-Indo-European*h₂énts
3. Proto-Indo-European*h₂énti
4. Ancient Greekᾰ̓ντῐ́ (ăntĭ́)
5. Ancient Greekἀντι- (anti-)
6. Englishanti-
7. Proto-Indo-European*tres-
8. Proto-Indo-European*troséyeti
9. Proto-Italic*troseō
10. Latinterreō
11. Latinterror
12. Old Frenchterreur
13. Middle Frenchterreur
14. Frenchterreur
15. Frenchterrorisme
16. Englishterrorism
17. English todayantiterrorism

From anti- + terrorism.