thyroidectomy

The story

1. Proto-Indo-European*dʰwer-
2. Proto-Hellenic*tʰurā
3. Ancient Greekθῠ́ρᾱ (thŭ́rā)
4. Ancient Greekθῠρεός (thŭreós)
5. Proto-Indo-European*weyd-
6. Proto-Indo-European*wéydos
7. Proto-Hellenic*wéidos
8. Ancient Greekεἶδος (eîdos)
9. Ancient Greekθῠρεοειδής (thŭreoeidḗs)
10. New Latinthyreoīdēs
11. Englishthyroid
12. Proto-Indo-European*h₁éǵʰ
13. Proto-Indo-European*h₁eǵʰs
14. Proto-Hellenic*eks
15. Ancient Greekἐκ (ek)
16. Ancient Greekἐκ- (ek-)
17. Proto-Indo-European*temh₁-
18. Ancient Greekτέμνω (témnō)
19. Ancient Greekἐκτέμνω (ektémnō)
20. Ancient Greekἐκτομή (ektomḗ)
21. English todaythyroidectomy

From thyroid + -ectomy.