-buterol

The story

1. Proto-Indo-European*tréyes
2. Proto-Indo-European*tri-
3. Proto-Indo-European*tritós
4. Proto-Italic*tritios
5. Latintertius
6. Englishtert-
7. Proto-Indo-European*gʷṓws
8. Proto-Hellenic*gʷous
9. Ancient Greekβοῦς (boûs)
10. Proto-Indo-European*tewh₂-
11. Proto-Indo-European*tuh₂rós
12. Proto-Hellenic*tūrós
13. Ancient Greekτῡρός (tūrós)
14. Ancient Greekβούτῡρος (boútūros)
15. Englishbut-
16. Proto-Indo-European*swel-der.?
17. Ancient Greekῡ̔́λη (hū́lē)
18. Englishbutyl
19. Englishtert-butyl
20. Englisharterenol?
21. English today-buterol

From (tert-)but(yl) + -terol.