intertracheal

The story

1. Proto-Indo-European*h₁én
2. Proto-Indo-European*h₁n̥tér
3. Proto-Italic*n̥ter
4. Latininter
5. Latininter-
6. Englishinter-
7. Proto-Indo-European*dʰreh₂gʰ-
8. Proto-Indo-European*dʰréh₂gʰus
9. Proto-Hellenic*tʰrākʰús
10. Ancient Greekτρᾱχεῖᾰ (trākheîă)
11. Late Latintrāchīa
12. Medieval Latintrāchēa
13. Englishtrachea
14. Proto-Indo-European*h₂el-
15. Proto-Indo-European*h₂élisder.?
16. Englishtracheal
17. English todayintertracheal

From inter- + tracheal.