centillion

The story

1. Proto-Indo-European*déḱm̥
2. Proto-Indo-European*ḱm̥tóm
3. Proto-Italic*kəntom
4. Latincentum
5. Latincenti-
6. Frenchcenti-
7. Englishcenti-
8. Proto-Indo-European*sem-
9. Proto-Indo-European*sm̥-
10. Proto-Indo-European*smih₂
11. Proto-Indo-European*ǵʰes-
12. Proto-Indo-European*ǵʰéslom
13. Proto-Indo-European*ǵʰéslih₂
14. Proto-Indo-European*smih₂ǵʰéslih₂
15. Proto-Italic*smīɣeslī
16. Latinmīlle
17. Italianmille
18. Italianmilione
19. Old Frenchmillion
20. Middle Frenchmillion
21. Middle Englishmilioun
22. Englishmillionbf.
23. English todaycentillion

From centi- + -illion.