thyroparathyroidectomy

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. Englishthyro-
13. Proto-Indo-European*per-
14. Proto-Indo-European*preh₂-
15. Proto-Hellenic*pərai
16. Ancient Greekπᾰρᾰ́ (părắ)
17. Ancient Greekπᾰρᾰ- (pără-)
18. Englishpara-
19. Englishthyroid
20. Englishparathyroid
21. Englishthyroparathyroid
22. Proto-Indo-European*h₁éǵʰ
23. Proto-Indo-European*h₁eǵʰs
24. Proto-Hellenic*eks
25. Ancient Greekἐκ (ek)
26. Ancient Greekἐκ- (ek-)
27. Proto-Indo-European*temh₁-
28. Ancient Greekτέμνω (témnō)
29. Ancient Greekἐκτέμνω (ektémnō)
30. Ancient Greekἐκτομή (ektomḗ)
31. English todaythyroparathyroidectomy

From thyroparathyroid + -ectomy.