etanidazole

The story

1. Proto-Indo-European*h₂eydʰ-
2. Proto-Hellenic*áitʰō
3. Ancient Greekαἴθω (aíthō)
4. Ancient Greekᾱ̓ήρ (āḗr)influ.?
5. Ancient Greekαἰθήρ (aithḗr)
6. Latinaethēr
7. GermanÄther
8. GermanEther
9. Proto-Indo-European*swel-der.?
10. Ancient Greekῡ̔́λη (hū́lē)
11. GermanEthy
12. Englishethyl
13. Englisheth-
14. Englishethane
15. Proto-Indo-European*médʰu
16. Proto-Hellenic*métʰu
17. Ancient Greekμέθυ (méthu)
18. GermanMethy
19. Englishme(thyl)
20. Egyptiannṯr
21. Egyptiannṯrj
22. Ancient Greekνῐ́τρον (nĭ́tron)
23. Englishnitro-
24. Egyptianjmn
25. Ancient GreekᾸ̓́μμων (Ắmmōn)
26. LatinAmmōn
27. Latinammoniacus
28. Englishammonia
29. Proto-Indo-European*dʰeh₁-
30. Englishamide
31. Englishimide
32. Proto-Indo-European*né
33. Proto-Indo-European*n̥-
34. Proto-Hellenic*ə-
35. Ancient Greekᾰ̓- (ă-)
36. Proto-Indo-European*gʷeyh₃-
37. Proto-Indo-European*gʷih₃wós
38. Proto-Indo-European*gʷíh₃weti
39. Proto-Hellenic*gʷyṓw-ō
40. Proto-Hellenic*d͏̌ṓwō
41. Ancient Greekζώω (zṓō)
42. Ancient Greekζῶ (zô)
43. Ancient Greekζωή (zōḗ)
44. Frenchazote
45. Englishazote
46. Englishazo-
47. Englishazole
48. Englishimidazole
49. Englishmetronidazole
50. English todayetanidazole

From etha(ne) + -nidazole (“metronidazole derivative”).