hyperthyroid

The story

1. Proto-Indo-European*úp
2. Proto-Indo-European*upér
3. Proto-Hellenic*hupér
4. Ancient Greekῠ̔πέρ (hŭpér)
5. Ancient Greekῠ̔περ- (hŭper-)
6. Englishhyper-
7. Proto-Indo-European*dʰwer-
8. Proto-Hellenic*tʰurā
9. Ancient Greekθῠ́ρᾱ (thŭ́rā)
10. Ancient Greekθῠρεός (thŭreós)
11. Proto-Indo-European*weyd-
12. Proto-Indo-European*wéydos
13. Proto-Hellenic*wéidos
14. Ancient Greekεἶδος (eîdos)
15. Ancient Greekθῠρεοειδής (thŭreoeidḗs)
16. New Latinthyreoīdēs
17. Englishthyroid
18. English todayhyperthyroid

From hyper- + thyroid.